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THE FUNDAMENTALS 
OF PSYCHOLOGY 



THE MACMILLAN COMPANY 

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THE FUNDAMENTALS 
OF PSYCHOLOGY 



BY 
Yt. Bf^ILLSBURY 

PROFESSOR OF PSYCHOLOGY 

DIRECTOR OF THE PSYCHOLOGICAL, LABORATORY 

UNIVERSITY OF MICHIGAN 



REVISED EDITION 



THE MACMILLAN COMPANY 
1922 

All rights reserved 



PRINTED IN THE UNITED STATES OP. AMERICA 




15/ 



COPTKIGHT, 1916 AND 1922, 

By THE MACMILLAN COMPANY. 



Revised Edition. Set up and electrotyped. 
Published September, 1922. 



Press of J. J. Little & Ives Co. 
New York 

SEP -6 1922 



©J.A681636 
^ f / 



PREFACE TO THE REVISED EDITION 

In the present revision I have made numerous changes in 
expression, have modified several sections that proved un- 
necessarily difficult for students, and have brought the sub- 
ject matter up to date. The major changes consist in the 
introduction of three entirely new chapters. One of these 
considers the differences in individuals at birth, and presents 
the methods of measuring intelligence, and the hereditary 
conditioning of intelHgence. This chapter also gives a pre- 
liminary discussion of the laws of learning. To complete 
the discussion of the innate differences, the chapter on In- 
stinct has been brought forward from the latter part of the 
book. The two other new chapters discuss respectively Im- 
agination and Dreams, with some reference to Freud, and 
Fatigue and Sleep. 

In the revision I have been much aided by suggestions 
from teachers in many institutions who have used the book, 
and especially by my colleagues and Dr. A. H. Sutherland. 
I desire to express my thanks to all of them named and 
unnamed. 

W. B. PILLSBURY. 

Ann Arbor, Michigan, 
August, 1922. 



Digitized by tine Internet Arcinive 
in 2011 with funding from 
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PREFACE TO THE FIRST EDITION 

This book is intended to fill a gap which exists to-day 
between the smaller texts and the reference hand-books. 
I have had in mind the needs of one of my own classes 
which devotes a year to psychology and includes students 
who have had no previous work in the subject. They have 
more than time to cover the present texts but are lost in 
the details of the larger works, particularly in connection 
with the nervous system, sensation, and perception. 

I have written for the student primarily and have not 
presupposed any preliminary knowledge. I have particu- 
larly avoided reference to current theories before they are 
explained and have indulged in no arguments on controver- 
sial matter for the benefit of colleagues rather than of the 
student. Opposing theories are discussed only as they may 
illumine statements of fact or where they have great his- 
torical importance and then only if the problem is real but 
is not settled. 

The technical psychologist may miss long discussions of 
general method and points of view I have replaced them 
by fuller statements of the results of experiment and more 
detailed treatment of the generally accepted body of facts. 
I have drawn upon the work of all schools without reference 
to the theories that the workers held, and have stated the 
results in terms that seemed most suitable to the particular 
material. Sensation and perception are discussed in struc- 
tural terms, action of all sorts in behavioristic terms. This 
gives some inconsistencies, but they are preferable to the 



viii PREFACE TO THE FIRST EDITION 

awkward phrases that would result from using the termi- 
nology of any school to the exclusion of the others. 

My own theory incHnes. towards a functionalism. The 
book is more concerned with what consciousness does than 
with what it is. As opposed to the extreme behaviorism, 
however, I am not concerned alone with understanding the 
movements of the organism and the function of the move- 
ments, but also with understanding knowledge and the way 
in which it develops. It is my belief that the content of the 
science is the same whatever the point of view from which 
the subject be approached, and that this content is essential 
and changes slowly and then through growth. The theories 
are less important and likely to change from decade to dec- 
ade. In contrast with some of the recent authors I have 
endeavored to supply the content and, while I have stated 
my own theories in some detail, have attempted to be suffi- 
ciently undogmatic to give the instructor opportunity to 
develop his own point of view. 

I take pleasure in acknowledging the help that has been 
given in the preparation of the manuscript by Dr. Adams, 
Miss Perkins, and my wife. All have read the manuscript 
or portions of it and have made numerous suggestions. The 
latter has also aided with proofs and index. Dr. Huber has 
aided much in the selection of illustrations for the neuro- 
logical portions, and at his suggestion Mr. Atwell of his lab- 
oratory has drawn sections for Figures 19, 21, 23, 24, 25, 
and 26. I express my gratitude to both. 

I also desire to thank the individuals and pubUshers who 
have permitted me to reproduce cuts: Professor Jennings 
for cuts from his "Behavior of Lower Organisms," Dr. Bar- 
ker for illustrations from his "Nervous System," W. B. 
Saunders & Co. for figures from Howell's "Text-book of 
Physiology" and Huber's "Histology," to Rebmann Bros. 



PREFACE TO THE FIRST EDITION ix 

for cuts from Bing's "Regional Diagnosis," and to The 
Macmillan Co. for cuts from Titchener's "Text-book of 
Psychology," from Thorndike's "Animal Mind," and Fos- 
ter's "Physiology." 

W. B. PiLLSBURY. 

Ann Arbor, Michigan, 
April 25, 1916. 



TABLE OF CONTENTS 

Chapter Page 

I. INTRODUCTION i 

Nature of Psychology 2 

Scope of Psychology 8 

Subdivisions of Psychology 11 

II. THE NERVOUS SYSTEM 15 

Behavior of Lower Organisms 15 

Nerve-cells in Man 19 

General Plan of the Nervous System . . 24 

Spinal Cord 39 

Brain Stem 46 

Paths in the Brain Stem 48 

Cerebellum, Corpora Quadrigemina, and Thal- 

Mus 57 

III. THE NERVOUS SYSTEM (continued) .... 60 

Functions of the Cerebrum 60 

Synapse 77 

Interaction of Impulses 81 

Consciousness 83 

Autonomic Nervous System 84 

Ductless Glands 85 

Body and Mind 88 

IV. SENSATION 93 

General Remarks 93 

Vision 97 

Structure of the Eye 98 

Sensations oj Light 109 

V. SENSATION (continued) 136 

Audition 136 

Structure of the Ear 136 

Sensations of Tone . 142 

xi 



xii TABLE OF CONTENTS 

Chapter Page 
V. SENSATION (continued) 

Tactual Sensations ,157 

Temperature . ■ 158 

Pressure and Pain 162 

Sensations of Taste 170 

Sensations of Smell . 176 

KiNiESTHETIC SENSATIONS l8l 

Sense of Equilibrium 183 

Organic Sensations 188 

Doctrine of Specific Energies 190 

Studies in Sensation Intensities — Weber's 

Law 193 

VI. THE ORIGINAL NATURE OF MAN, AND THE 

MEANS OF MODIFYING BEHAVIOR . . 199 

Intelligence Tests 202 

Character Tests . 207 

Individual Differences 208 

Habit Formation 212 

VII. INSTINCT 219 

Nature of Instinct 219 

Specific Instincts 224 

Instinct and Conduct 233 

Origin of Instinct 237 

VIII. RECALL AND THE QUALITIES OF RECALLED 

EXPERIENCES 241 

Retention 242 

Association 246 

Images, or Centrally Aroused Sensations . . 254 

Imagery Types 258 

IX. ATTENTION 265 

Nature of Attention 265 

Motor Aspects of Attention 268 

The Limits of Attention 273 

Conditions of Attention 277 

Attention and Association 284 

Forms of Attention 288 

Physiological Basis of Attention .... 291 



TABLE OF CONTENTS xiii 

Chapter Page 

X. PERCEPTION . 294 

General Remarks 294 

Perception or Space 298 

Auditory Space 325 

Illusions in Space Perception 329 

XL PERCEPTION (continued) 344 

Perception of Movement 344 

Rhythm 349 

Perception op Time 352 

General Laws or Perception 356 

XII. MEMORY '.365 

Memory of Objects and Events 366 

Rote Memory 368 

Laws of Learning 369 

Retention and Forgetting 380 

Recall 384 

Recognition 387 

Meaning an Aid to Memory 397 

General Aspects of Memory 401 

XIII. REASONING 407 

Meaning 410 

Concepts 414 

Initiation of the Reasoning Process . . . 424 

Judgment 424 

Inference 427 

Belief and Proof 430 

General Remarks on Reasoning 437 

XIV. IMAGINATION AND DREAMS 441 

Play 442 

Revery 444 

The Unconscious . 446 

Dreams 448 

Other Experiences of the Unconscious and a 

Critique of Freud's Theory 451 

Art 454 

General Remarks on Imagination .... 456 



xiv TABLE OF CONTENTS 

Chapter 

XV. FEELING AND AFFECTION 458 

Affection 460 

Other Aspects of Feeling 468 

Theories of Feeling . 474 

XVI. EMOTION AND TEMPERAMENT .... 480 

Characteristics of Emotion 481 

Bodily Responses in Emotion 487 

General Aspects of Emotion 494 

Other Mental States Related to Emotion . 503 

XVII. GENERAL PRINCIPLES OF ACTION, AND THE 

WILL 508 

Learning 510 

Movement 520 

Choice 528 

The Will 531 

XVIII. WORK, FATIGUE, AND SLEEP 538 

Work 538 

Fatigue 541 

Sleep 556 

XIX. THE SELF 560 

Nature of the Self 561 

Continuity of the Self 572 

Dissociations of the Self 575 

The Self as the Whole Man Active . . . 579 

Index of Names 583 

Subject Index 586 



THE FUNDAMENTALS 
OF PSYCHOLOGY 



FUNDAMENTALS OF 
PSYCHOLOGY 



CHAPTER I 
INTRODUCTION 

It is easier to say what psychology discusses and to 
point out the ends of its discussions than to give a formal 
definition. Psychology is the science which deals with the 
activities commonly known as mental, the processes of 
perceiving, of remembering, of thinking, and particularly 
with the acts of the individual. As in any other science, 
the aim is first to determine what these activities are, what 
they do, and then to trace them to their conditions, to un- 
derstand them in the hght of every fact that can have any 
bearing upon them. It is easier to show what psychology 
is and what its aims are by concrete illustration than by 
abstract statements. 

Take memory, for example. Psychology is concerned 
with knowing all that is possible of how we learn and 
remember. Every one is familiar with memory in a purely 
objective way. A lesson is studied and, when occasion 
arises, much of it can be repeated. How one remembers, 
troubles the ordinary individual very little. When ques- 
tioned he knows almost as little of how he remembers as 
does the questioner. The task of psychology is to discover 
the laws and conditions of learning and recall in all of their 
details. It must know what methods lead most certainly 



2 FUNDAMENTALS OF PSYCHOLOGY 

and quickly to a first learning, what kind of learning will 
permit retention for the longest time, and how forgetting 
takes place. These investigations have been carried out in 
great detail, as will be seen in a later chapter. While mem- 
ory itself is regarded as a mental process, the measurements 
of memory are as objective as are measurements of the 
strength of materials, although of course the variation is 
greater from measurement to measurement. The experi- 
ments require somewhat complicated special apparatus and 
a special training in manipulation, and the methods used 
and the results obtained may be stated in terms that make 
no mention of mind. Thus, the most satisfactory rate for 
retention, the best method of distributing the repetitions, 
the rate of forgetting, are determined by objective tests 
that hold irrespective of theory. It is also possible to study 
very many of the conditions of recall by objective methods. 
One may speak a word and then ask the observer to speak 
the first word that occurs to him. A study of the connection 
between these words permits a statement in a perfectly 
objective way of the laws that hold for recall. These are 
the facts with which psychology must deal. They may be 
collected in much the same way for each of the different 
activities of man. 

The Nature of Psychology 

Methods of Psychology. — This purely objective and 
experimental study of mental activities depends upon 
observation. It may be carried on for man in exactly the 
same way as for animals, by making experiments from the 
outside, with no attempt to discover directly what has been 
going on within the individual. But this is not the only 
method of psychology. We may also make use of the 
individual's report on the processes. He can observe from 



INTRODUCTION 3 

within what accompanies and precedes the activities objec- 
tively measured. This, the process of self-observation or 
introspection, will in many cases supplement the results of 
direct observation, and the individual who is experimented 
upon can often supply an explanation when the observer can 
find none. While the fundamental causes of most mental 
phenomena are as much hidden from him as from the 
experimenter, he can add an account of accompanying 
phenomena that is nearly always suggestive, and may at 
times furnish a solution for the questions raised by the 
objective results. The two methods of psychology, then, 
are observation and introspection. One gives the phenom- 
ena as they present themselves to the onlooker, the 
other as they appear to the individual investigated. At 
present both methods are used under experimental condi- 
tions that make it possible to control the stimuli and to 
provide means of measuring many reactions that would 
escape either unaided observation or introspection. 

The Definition of Psychology. — While practically all 
are agreed as to the field which psychology is to study and 
on most of the results obtained, there is and always has 
been much controversy over what it is that is studied. 
Three definitions are current at present which differ in the 
statement of the object to be studied : 

The first asserts that psychology is the science of 
mind, a direct translation of the original Greek. Two 
meanings are given to the word 'mind.' One regards it 
as something substantial, an actual thing or an actual 
force which produces certain effects or manifests itself 
in the phenomena we directly experience; the other, 
of more recent development, asserts that mind is just 
these manifestations, the sum of mental states without 
any assumption as to what it is that produces them. 



4 FUNDAMENTALS OF PSYCHOLOGY 

A second definition makes psychology the science of 
consciousness. Consciousness, like mind in its second 
definition, is just the series of mental phenomena., the 
memories, thoughts perceptions, emotions and feelings 
as they are immediately experienced. 

A third definition, most recent of all, defines psy- 
chology as the science of behavior. By behavior is 
meant the activity of the man or animal as it can be 
observed from the outside, either with or without 
attempting to determine the mental states by inference 
from these acts. 
The various definitions can be illustrated concretely 
in the memory process. As theory of mind, psychology 
regards memory as one of the manifestations of mind and 
either is concerned with understanding mind through this 
manifestation or is content to describe remembering as one 
of the mental capacities. In fact, earlier theories of mem- 
ory were content to assert that ideas were stored in 
mind or that they were impressions made upon a waxen 
plate. In either case, no details could be given as to how 
they were stored or how they might be reinstated. Mind 
was both an active agent and a receptacle, the sole means of 
accounting for mental states. If mind is to be defined as the 
sum-total of mental states in accord with the more recent 
suggestions, it is practically synonymous with consciousness, 
— the first definition merges into the second. As science of 
consciousness, psychology is concerned with a description 
of the different memory images, with the determination of 
the order of their appearance and with all else that is related 
to their structure and function. It takes into consideration 
nothing that is not to be discovered by the individual who 
remembers. It excludes consideration of mind as a store- 
house, for that is not open to observation ; and also of mind 



INTRODUCTION 5 

as a wax plate or other similar entity. All that it can do 
is to determine the laws of succession of the mental states, 
and to describe the mental states themselves. As science of 
behavior, psychology only need investigate the capacity of 
the individual to remember. The individual is asked to 
repeat words or syllables a certain number of times under 
different conditions. After a certain period or certain 
periods he is tested to see how many he remembers. From 
these results laws can be formulated for the most effective 
means of learning. 

The second and third of these definitions are alike in that 
neither implies any theories concerning what cannot be 
seen, what is not open to observation. Each would content 
itself with observation, from within or from without, of 
what actually takes place. As in all sciences, each form of 
observation may be subjected to experiment, the condi- 
tions of learning may be varied at will, the corresponding 
changes in results noted and formulated in laws. The choice 
between them must be made in terms of the methods that 
each emphasizes, and on the basis of the accuracy with 
which each can be made to cover the facts that are to be 
included under psychology. In strict definition, all is at 
once consciousness and behavior for most individuals. Few 
would deny that all behavior, to be known, must become 
conscious, either to the actor or observer; and none would 
deny that consciousness, unless it is to remain forever indi- 
vidual, must express itself in behavior. The choice of the 
definition 'science of behavior' turns, first, upon the fact 
that consciousness tends to imply something removed from 
observation, something mystical, a thing, rather than a 
series of phenomena; secondly, upon the fact that behavior 
is the more inclusive term; and finally, upon the doubt 
expressed by recent writers as to whether consciousness 



6 FUNDAMENTALS OF PSYCHOLOGY 

exists, at least exists for them individually. It emphasizes 
the fact that laws of action must first be discovered, and 
that theories and theoretical explanations must be derived 
from the actual results of experiment and observation, 
rather than be accepted in advance. 

Behaviorism. — The most recent development in method 
and theory has grown naturally from the great progress 
that has been made in animal psychology. Experiments on 
animals are of necessity Hmited to an observation of what 
the animal does under rigidly determined conditions. 
(Some of the earlier psychologists made inferences from 
the observed movements as to what mental processes might 
accompany them, but the results were so unsatisfactory 
that all assumptions about the consciousness of animals 
were abandoned.) The success in applying the method of 
purely objective experimentation to animals emphasized 
the possibiHty of applying the same method to man. If 
one could develop the laws of man's action by a study of his 
responses under different conditions, it would not be neces- 
sary to accept the unconfirmed statements of the observer, 
and would make it possible to check each observation by 
several individuals or to record them graphically. So far 
as it can be appHed, the method offers obvious advantages 
and should be pushed to the fullest extent. Whether this 
can be the only method in psychology is still a matter of 
debate. Certain of the questions which interest the psy- 
chologist concern mental states, and these have been an- 
swered by the older methods. Up to the present time no 
objective investigations of these problems have been made, 
and we must either omit them or state the results of the 
older methods on the older presuppositions. Watson, the 
extreme behaviorist, relieves himself of the difficulty by 
omitting all mention of mental states, and by asserting 



INTRODUCTION 7 

that if they do exist they cannot be made the basis of 
a science. Many of his more moderate followers are con- 
tent with emphasizing the desirability of the objective 
method where available. Consciousness seems to them a 
fact of immediate experience. If it exists it should be taken 
into account in a study of behavior, when it contributes 
relative data. All psychologists, of whatever school, will 
hail with delight the fullest appHcation of the objective 
methods; the behaviorists that it may supplant, others 
that it may supplement, introspection. 

The three definitions do not differ essentially as to what 
the phenomena of consciousness are, nor as to the general 
laws that express them, but rather in the theoretical expla- 
nations which each offers. Thus the exponent of the extreme 
behaviorist view differs from the extreme subjectivist not 
in the facts he accepts but in that he does not believe that 
consciousness exists, or if it exists, that it plays any impor- 
tant part in controlling action. For the subjectivist, on the 
other hand, consciousness seems the final term by which 
all else must be explained; behavior is secondary. In the 
first definition, the use of mind is very obviously the intro- 
duction of a theoretical explanation. No one claims that it 
is ever open to direct observation, however important it 
may appear to the individuals who beHeve in it. These 
differences of opinion on theoretical points may very well 
be neglected in the development of a description of the 
mental Hfe. After facts have been collected and laws for- 
mulated, the fundamental problems may be attacked in 
the fight of those results. Laws are bound to suggest wider 
generafizations, and these in turn reveal fundamental causes 
or conditions. 

Psychology Treats Only Certain Phases of Behavior, — 
Obviously, if we are to define psychology as the science of 



8 FUNDAMENTALS OF PSYCHOLOGY 

behavior, we must limit its application, since all of the 
biological and even the chemical and physical sciences are 
needed to explain behavior in its completeness. In practice, 
we Hmit ourselves to the explanation of intelHgent behavior. 
Roughly, behavior may be regarded as intelHgent when it 
is modified by the earher experience of the organism. All 
the acts of certain of the lowest organisms and some of the 
acts of the highest are to be explained altogether in terms 
of the physical stimuli and of the constitution of the organ- 
ism. In consequence, these responses are relatively invaria- 
ble, — the organism makes the same movements under 
the same conditions; such responses do not concern psy- 
chology. When behavior is modified, not merely by the 
physical stimuli and chance chemical conditions of the 
organism, but also by the results of earher behavior, we 
have the first beginnings of intelHgence, and the organism 
offers material for- psychology. \Even in the highest organ- 
isms, psychology is concerned only with the phases of be- 
havior which cannot be referred directly to chemical and 
physical changes within and without the organism. It 
deals in general with the acts of the organism as a whole, 
rather than of the parts, and it considers the acts of the 
organism only in so far as they are not explained by physi- 
ology and other distinctly biological sciences. In general, 
again, psychology treats behavior in so far as it is deter- 
mined by previous acts of the individual, by other more 
remote influences, while the other sciences treat the same 
behavior in so far as it is due to the activities of particular 
organs and to the more mechanical forces. 

The Scope oe Psychology 

Psychology in its Relation to Other Sciences. — If part 
of all behavior is to be explained by other sciences, by 



INTRODUCTION 9 

physiology, by anatomy, and the other biological sciences, 
the psychologist must take the results of these sciences into 
consideration. He must know what part of the problem 
they solve and what they leave over for him to discuss. He 
must also use many of their results in attaining his own con- 
clusions. Knowledge of the structure and function of the 
nervous system is particularly important, as in the higher 
organisms practically all behavior is an expression of 
nervous action. Capacity for the more complex forms of 
behavior develops with the nervous system, and defects in 
the nervous system are closely correlated with deviations 
from normal behavior. Consciousness, too, is closely related 
to the nervous system. One can become aware of external 
objects only as stimuli are carried to the brain by the sensory 
nerves; memory defects accompany injuries to definite 
portions of the brain tissue. In fact, we have every reason 
to believe that all forms of consciousness have definite 
accompaniments in the nervous system. Viewed from any 
standpoint, the problems of psychology are closely bound 
up with the problems of the nervous system. A knowledge 
of nervous anatomy and physiology is essential to an under- 
standing of either consciousness or behavior. We shall 
begin our work with a brief survey of the more important 
facts of neurology. This survey, it may be well to state, is 
not part of the field of psychology. It is given here only 
because one cannot presuppose that all readers have a 
knowledge of the nervous system, and acquaintance with 
the facts is necessary to an understanding of many defi- 
nitely psychological problems. A full preparation for com- 
mencing the study of psychology makes requisite also the 
results of physics and chemistry. All of the activities of 
the organism involve chemical processes, and the stimuli 
to action are physical. In brief, all of the sciences dealing 



lo FUNDAMENTALS OF PSYCHOLOGY 

with any of the forces that arouse or modify action and with 
the nature of the organism itself must be of assistance to 
psychology. 

In addition to the sciences to which psychology must look 
for aid in solving its problems, it also has close relations 
with many of the social sciences, which either depend upon 
it or share with it in the solution of their own problems. 
Sociology in its attempt to understand society must take 
into consideration the individuals of which it is composed, 
and welcomes whatever Kght psychology can shed on the 
subject. In many of its phases sociology is social psychology. 
Similarly, much of the work in economics depends upon a 
knowledge of mental laws. The economist, however, has 
for the most part developed his laws of human nature for 
himself from a study of practical relationships, rather than 
from the findings of psychology. The relationship of psy- 
chology to philosophy is, for the theoretical problems, 
closest of all. Psychology was the latest of the sciences to 
separate from philosophy, and the attitude toward many 
of the fundamental problems is still profoundly influenced 
by philosophical considerations. Each of the definitions of 
psychology discussed has developed in response to philo- 
sophical theories. On the other hand, many of the philo- 
sophical discussions presuppose a knowledge of psychology. 
There has always been an interaction between the two 
disciplines. 

Subdivisions of Psychology 

The Varieties of Psychology. — The more usual classifi- 
cations of psychology have been based upon the ways of 
approaching the subject, upon the methods used in the 
investigation, or upon the field that is treated. The older 
psychologies were divided into rational or deductive, and 



INTRODUCTION ii 

empirical or inductive (on the basis of the fundamental 
method employed). Recently all psychology has tended to 
become empirical or inductive, particularly with the in- 
creased use of experiment; and the method of deduction 
has been appHed only to topics that do not lend themselves 
to experiment or observation. Rational psychology as a 
separate field has largely disappeared. Even Wolff, who 
may be said to have introduced and certainly to have made 
large use of the distinction, was not able to keep the two 
apart; but was continually turning from one to the other. 
Two branches have received names from the direction of 
approach: physiological psychology and psychophysics. 
The former treats of the mental processes in their relation 
to the nervous system and its action. It is implied in all 
forms of psychology at the present time and differs from the 
others for the most part only in the relative amount of space 
devoted to the physiological aspects. All psychologists at 
present presuppose a knowledge of the nervous system and 
its action, even if they do not discuss it explicitly. Much 
the same may be said of psychophysics. This lays greatest 
emphasis upon the part the physical stimuli play in 
mental processes, and the way in which mental states 
change with changes in physical stimuli. Both physiologi- 
cal psychology and psychophysics were titles of important 
works on psychology, the one by Wundt, the other by 
Fechner. Closely connected with physiological psychology 
is objective psychology, a name given to several recent 
books. This not merely places the emphasis upon the 
nervous system and its activity, but actually leaves con- 
sciousness out of consideration altogether. It, like be- 
haviorism, studies behavior from the outside only. 

Different Fields of Psychology. — Psychology may be 
divided with reference to subject matter. Most psychology 



12 FUNDAMENTALS OF PSYCHOLOGY 

deals with the adult human individual, but recently many- 
additional and special fields have been developed. 

Social Psychology. — Society, or man in the mass, may be 
studied, as well as the individual. A society shows many 
characteristics different from and in addition to the qualities 
of the individual. A mob, for example, will do many things 
that few if any of the individuals who compose the mob 
would countenance in calm moments. These and other 
phases of group psychology have been studied, and a series 
of important laws developed. Race psychology deals with 
the broader mental differences between races and is a 
natural extension of social psychology but has been less 
fully developed. 

Genetic Psychology. — A second group of divisions of 
psychology, genetic psychology, treats the less developed 
types, either with the object of throwing Hght upon more 
complex human behavior or for their own sake. The most 
fully developed of these is animal psychology. The question 
as to whether or not animals are intelHgent and how their 
intelligence compares with man's has always interested 
students, but until within the last two decades most of the 
conclusions were based upon anecdotes or, at most, upon 
the chance observations of travellers and naturahsts. These 
were obviously not trustworthy. More recently, experi- 
ments upon animals have been carried on by both biologists 
and psychologists, with very important results. The be- 
havior of typical animals from the protozoa to the apes 
has been studied exhaustively. Much light has been thrown 
upon their own activities, and many points in human psy- 
chology have also been illuminated by these results. The 
development of the individual has also been investigated. 
Child study has offered a number of conclusions that make 
easier an understanding of the compHcated activities of 



INTRODUCTION 13 

man. The earKest years and the period of adolescence have 
received most attention. 

Abnormal Psychology. — -Still another important series 
of problems has arisen in connection with different forms of 
mental deterioration, the psychology of the abnormal, or 
pathological psychology. The relation of these studies to 
normal psychology has been twofold. They have greatly 
aided in an understanding of the normal individual. One 
is very much more certain that a voluntary act depends 
upon certain stimuli or sensations when it can be shown that 
the absence of that stimulus causes a defect in the move- 
ment. Disturbances of the self have given a more profound 
knowledge of what the self is or is not than centuries of 
speculation and introspection. Slighter defects of sensa- 
tion, color bhndness and partial deafness, not to mention 
the impairment of memory and related processes, have all 
given valuable aid in the unravelling of psychological prob- 
lems, or have substantiated results obtained in other ways. 
On the other hand, psychological methods and psychological 
results have been adapted to the study of the abnormal and 
defective minds with much theoretical and practical benefit. 
Certain standardized tests have come into use which make 
it possible to determine within fairly close Hmits the degree 
of intelligence of the individual. These have proved of value 
in the schools in selecting the children who are unable to 
profit from the usual training, and make it possible to give 
them special instruction. It has been shown by an exami- 
nation of criminals and paupers that, in a large number of 
cases, a mental defect is responsible for their failure to fit 
into society; and the necessity for special care that shall 
provide the ounce of prevention has been emphasized. 
Many of the methods used to-day for the diagnosis of 
insanity have also been developed in psychological labora- 



14 FUNDAMENTALS OF PSYCHOLOGY 

tories, and much of the treatment has been an outgrowth 
of psychological principles, an application of psychological 
methods. 

Our Problem. — In this work we shall restrict ourselves 
to a study of the normal adult human individual. Reference 
will be made to the other branches of psychology only in 
so far as their results aid us in understanding this central 
problem; they render valuable aid at practically every 
point. We shall use the results of all methods, but shall 
enter as little as possible into the controversies as to whether 
any one method is theoretically justifiable. We shall assume 
that there is a body of fact that is independent of the 
theoretical discussions. Thus, in connection with the dif- 
ference of opinion as to whether observation or introspec- 
tion is the method in psychology, we shall remain neutral, 
and make use of the contributions of each method. After 
all, the controversy concerns us only in its effect upon the 
form of expression that may be used to state the results 
rather than in the validity of the results themselves. Most 
of these results may be expressed equally well in terms of 
one theory or the other, and where they cannot we shall 
use the terminology best suited to the particular statements 
in hand. The facts are important and will persist, while 
the theories that interpret them are in constant flux. We 
shall be concerned primarily with facts, and the theories 
will be considered only where they serve to make clear the 
facts. 

REFERENCES 

Angell: Chapters in Modern Psychology. 

Watson: Psychology from the Standpoint of a Behaviorist, 
Ch. I. 

Bertrand Russell: The Analysis of Mind. 

Warren: Human Psychology, Ch. I. 

Woodworth: Psychology, Ch. I. 



CHAPTER II 

THE NERVOUS SYSTEM 

Broadly speaking, the physical basis of mind is to be 
found in the nervous system. In a very general sense, the 
nervous system is the organ of mind. When, however, we 
approach it from the physical side, it is also the organ which 
makes possible the activities of the body, which permits 
external stimuli to act upon the muscles, and coordinates 
the different movements so that they may bring about har- 
monious and unified action. An understanding of the action 
and even of the structure of the nervous system is very 
much easier if we keep the emphasis upon the relation of 
the nervous system to bodily movement — treat it first for 
itself — ■ than if we think of it in its relation to consciousness. 
The problem of the relation of body and mind may be 
taken up when we know more of body. The nervous system 
in vertebrates is made up of the brain and spinal cord with 
the sensory and motor nerves that extend from these cen- 
tral organs to the sense organs and muscles. The brain fills 
the upper part of the skull, while the spinal cord is found in 
the spinal column. The details of the structures can be 
understood more readily if we consider them later in con- 
nection with their development in the race and in the 
individual. 

Behavior of Lower Organisms 

Life Processes in Cells. — It is much easier to understand 
the action of higher animals and the nervous structures 

IS 



i6 



FUNDAMENTALS OF PSYCHOLOGY 



themselves if we commence by describing briefly the animal 
organisms which do not possess nerve tissue, the so-called 
unicellular organisms. This is the type of organism from 
which all the higher forms are assumed to have developed. 
Of the single-celled animals, or protozoa, one that is most 




Fig. I. — Amceba chasing and attempting to ingest a euglena. (From Jennings.) 

frequently used to illustrate the type is the amceba. It is 
merely a drop of Hquid of unknown but highly complex 
chemical composition contained in a dehcate semipermeable 
membrane. Since this is the original tissue from which all 
other Kving matter is developed, it is known as protoplasm. 
We know that protoplasm is made up of highly unstable 
chemical compounds, mostly hydrocarbons, but the differ- 
ent components have never been completely isolated 



THE ACTIVITIES OF PROTOZOA 17 

or analyzed. Whatever the composition of this chemical 
substance, it is constantly undergoing change. It takes to 
itself other organic compounds and oxygen and gives ofif 
carbonic acid. It is constantly taking something from the 
medium in which it Hves and giving off waste products. 
Both of these changes take place through the semipermeable 
membrane by a process which the physicist calls osmosis. 
Within the body of the cell is a darker spot, known as the 
nucleus. This nucleus is closely connected with the nutri- 
tive processes and the subdivision of the cell. Much still 
remains to be known of the life processes in the cell. We 
can only give the briefest account of what is known — - that 
some chemical processes must go on within the cell, that 
the materials involved are admitted to the cell by osmosis - 
through the membrane, and that these processes taken to- 
gether make possible, if they do not constitute, what we 
call life. 

The Activities of Protozoa. — If we study the activities 
of one of the unicellular organisms, we find that in a simple 
way it can do almost everything that the most highly 
organized animal can, and that it follows the same funda- 
mental laws of behavior. It takes nourishment, it breathes, 
and, what is most important from our point of view, it 
moves upon stimulation of any part. If particles of a cer- 
tain chemical composition come into contact with its 
membrane, it enfolds them, and the process of digestion 
through the membrane of the cell begins. If other particles 
of another kind come into contact with it, it moves quickly 
away. When in contact with a solid body, it may send out 
a prolongation of its body in the form of a foot or what is 
known as a pseudopod (false foot) which attaches itself 
to the surface, and the whole body then draws itself up to 
the foot, which is then withdrawn into the rest of the body. 



FUNDAMENTALS OF PSYCHOLOGY 






The single cell is stomach, lung, and organ of locomotion, in 
one. 

Study of the responses of the amceba and of the stimuH to 
which it responds shows its similarity to the higher organ- 
isms. When stimulated 
gently by a soHd surface, 
its activity is not changed, 
but, if the excitation is 
stronger, it at once stops 
all movement and rolls up 
into a ball. If the stimu- 
lation is continued, it may 
send out a pseudopod on 
the opposite side and roll 
away from the stimulus. 
In these two ways the 
protozoa respond to light, 
heat, the motion of the 
Hquid medium, the attrac- 
tion of gravitation, and to 
the presence of chemicals 
in the Hquid. In general, 
beneficial stimuH have no 
effect, while harmful stim- 
uli cause a movement that 
removes the organism from 
its neighborhood. Certain organisms, the Stentor that Jen- 
nings worked with, for example, modify their reactions in 
accordance with the result of earlier reactions, and thus 
give the first evidence of learning. If we use variability of 
response as a mark of intelhgence, this may be regarded as 
an intelKgent act. The first response of the Stentor when 
stimulated is to withdraw into its tube. After this has 




Fig. 



!. — Stentor stimulated by carmine 
particles. (From Jennings.) 



MAN A COLONY OF CELLS 19 

been repeated several times, it changes its form of response 
to bending to one side to escape the contact. Later it may, 
when strongly and repeatedly stimulated, loosen its hold 
on the tube and swim away. These latter responses were 
called out by permitting water mixed with carmine parti- 
cles to reach its disk. 

Each of these responses is to be thought of as the result 
of the transfer of a chemical stimulus from the point of 
stimulation to a more or less remote portion of the cell 
where the movement is made. Did we know the exact 
nature of the processes in these simplest cells, many of the 
problems of man's action would be solved. So far we have 
only commenced in that direction, although advances are 
being made frequently. At the present stage of our knowl- 
edge we can do no more than express the beHef that a 
chemical or physical explanation may some day be found. 
Meanwhile we may use the action of these simple organ- 
isms as a type of the action of cells in general. 

The Nerve Cells in Man 

Man a Colony of Cells. — These responses are important 
for us from the fact that one may think of all of the higher 
organisms as compounded of cells like these simple unicel- 
lular organisms, which have undergone various modifica- 
tions as a result of living together in a colony, but still re- 
tain many of the characteristics of the original free-swim- 
ming protozoa. For our present purposes, the body of 
man may be pictured as a mass of cells in which each class 
has developed speciaKzations that fit it to fulfil some one 
function. With increased capacity for this function, others 
of the primitive capabilities have been lost. Nevertheless 
the rudiments of all the capacities of the complex organ- 
isms are to be found in the unicellular organisms. In the 



20 



FUNDAMENTALS OF PSYCHOLOGY 



body, the nerve cells are among the least modified. Unlike 
the bone cells, for example, that become so filled with salts 
as to retain but slight sirriilarity to the original, the nerve 
cells lack motion alone of the capacities of the prototype. 
Only certain of the blood corpuscles retain more of the 
original properties; the leucocytes, or white blood corpus- 




FiG. 3. — A group of human nerve-cells drawn to the same scale, a, small cell 
from the ventral horn of the cord; b, cell from Clarke's column; c, small nerve-cell 
from tip of dorsal horn, thoracic cord; d, spinal ganglion cell, cervical root; e, three 
granules from cerebellum; /, Purkinje cell from cerebellum; g, small pyramidal cell 
from second layer of central gyri of cortex; h, giant pyramidal cell from same 
region. (From Donaldson, after Adolf Meyer.) 

cles, seem to live almost as independent an existence in the 
blood as the amoeba in its watery medium. 

Morphology of Neurones. — The cells of the nervous 
system have retained especially the sensitivity and con- 
ductivity of the unicellular forms. In brief, the elements 
of the nervous system, known as neurones (also spelled 
neurons), consist of a central cell, the representative of 
the cell body, and numerous processes that extend in all 
directions from that cell body. The cell body is of a more 
or less irregular shape and varies in diameter from about 



MORPHOLOGY OF NEURONES 



21 



2^ to To of a millimetre. The shapes can be seen from the 
accompanying diagrams. Within the body of the cell are 
found a nucleus and a nucleolus, as in all cells. Within the 




Fig. 4. — Cells from the cord of a rabbit, showing internal structures. A, B, C, 
motor cells; Z), small cell from the spinal root ; a, bundles of neurofibrils; c, perinu- 
clear plexus; d, the empty areas correspond to the Nissl bodies; e, section of a den- 
drite, showing similarity to cell tissue. (From Cajal.) 

protoplasm are small particles that stain easily, named 
Nissl or tigroid bodies, the former after their discoverer. 
In many cells can also be seen fine fibrils that run through 
the bodies of the cells and into the processes. It is not pos- 



22 



FUNDAMENTALS OF PSYCHOLOGY 



sible, however, to assert positively what function these dif- 
ferent parts of the cell have. The nucleus and Nissl bodies 
are probably closely connected with the nutrition of the 
cell. Some theories assign a highly important function to 
the fibrils, but the balance of opinion seems opposed to re- 
garding any one part of the cell as the fundamental seat of 
its activity. We cannot as yet analyze the action of the 
cell into elements, but must think of it as acting as a unit. 
Axones and Dendrites. — The processes or extensions of 
the neurones are of two sorts, distinguished rather by func- 
tion than by structure. One, which serves to conduct im- 
pressions away from the cell body, is usually long, with 
relatively few branches, and these at right angles to the 
main stem. It is called the axone (also spelled axon). The 
axone terminates in the end brush, a 
number of short branches, each of 
which is probably continuous with a 
fibril in the axone. The other is usually 
made up of a number of fibres much 
shorter and much branched, is in fact 
usually a thick network Kke the roots 
of a tree, an appearance that gives the 
whole its name, the dendrite. This 
usually carries impressions to the cell 
body. The axones may be of consider- 
able length. A single axone extends 
from the brain to the lower cord in 
the case of the motor fibres and sensory 
axones from the cord to the medulla. The axones carry 
impulses away from the cells. The dendrites are nearly 
always relatively short, less than a milhmetre in length. 
The one striking exception is found in the case of the 
dendrites of the sensory neurones whose cells are found 



r- Nucleus 



'T'- shaped 



cell from spinal ganglion 
of frog. (From Boehm- 
Davidoff - Huber's "His- 
tology.") 



THE SHEATHS OF THE AXONES 23 

in the spinal gangKa, masses of nerve tissue near the 
cord. They serve to transfer impressions from the organs 
of the skin and lower body to the cord and brain. The 
process that runs to the skin may be two feet or more 
in length, extending from the skin of the toe, for example, 
to the T-shaped cell body in a spinal ganghon in the lower 
part of the back. In appearance it is not to be distin- 
guished from the fibre of an axone, but its function is to 
carry an impulse to the cell, the function of a dendrite. It 
is sometimes called a teledendrion, or long dendrite, to 
avoid the difficulty of classing it either with the axone or 
with the dendrite. 

The Sheaths of the Axones. — The axones do not show 
a homogeneous cross section, but consist of several parts. 
In the centre is a core of protoplasm continuous with the 
structure of the cell body. In it may be traced the minute 
fibrils that were mentioned above as found in the cell. 
About this central core of nervous tissue are found one or 
two coverings or sheaths. One, the outer, known as the 
neurilemma, or sheath of Schwann, is a thin white layer, 
segmented or notched at intervals. Many fibres have 
within this outer sheath a thicker coating of fatty sub- 
stance known as the medullary or myehn sheath. This is 
absent in the nerves of the sympathetic system and at the 
early stages of the development of the fibres in the brain. 
The neurilemma is found on the peripheral nerves, but is 
lacking within the central nervous system. The axone 
lacks both sheaths, too, for a short distance after it leaves 
the cell body and the end brush is also always bare. Flech- 
sig has inferred that the medullary sheath is necessary for 
the action of brain fibres from the fact that this sheath de- 
velops successively on different groups of fibres, as the in- 
dividual grows older before and after birth, and that fibres 



24 FUNDAMENTALS OF PSYCHOLOGY 

continue to be medullated up to and beyond middle age. 
The facts that some fibres are always without this sheath 
and that animals can learn before their cerebral fibres are 
medullated make its importance somewhat doubtful. The 
central core, then, may be regarded as the path of the im- 
pulse, and the sheaths as largely protective. In a periph- 
eral nerve several thousands of these fibres may be 
united. In the optic nerve it is estimated that there are 
100,000 of them grouped together. Between the nerve 





Fig. 6. — Longitudinal and transverse sections of a medullated nerve fibre. The 
myelin sheath is shown in black; the central protoplasm shows its fibrous structure. 
(From Barker, after Biedermann.) 

cells are numerous cells of a different character, the neu- 
roglia cells. They are supposed to have no part in the con- 
ductivity of the nervous system, but to constitute support- 
ing structures. Their exact function is not known. Their 
shapes may be seen in Figure 7. 

The General Plan of the Nervous System 

The General Outlines of the Nervous System. — The 
nervous system of man is altogether made up of these neu- 
rones held together by their own cohesion and the pres- 
sure of the bones and other surrounding tissues. The pe- 
cuHarities of appearance of the different structures are due 
to the way in which the different elements are combined to 




GENERAL OUTLINES OF NERVOUS SYSTEM 25 

constitute the masses. As one looks at the nervous system 
of a mammal, one may distinguish three parts. The largest 
is the cerebrum, which fills the upper portion of the skull, 
next below is the brain stem, so called because it may be 
regarded as supporting the brain proper. The largest part 
of this is the cerebellum, which lies in man just below the 
cerebrum, although it is attached 
to the brain stem below several 
of the other important structures. 
In the brain stem between the 
base of the cerebrum and the 
point of attachment of the cere- 
bellum are the corpora quadri- 
gemina and the thalami. The 
latter are at the base of the cere- 
brum, the former just below it. Fig. 7.— Neuroglia cell. In 
mi 1 . 1 11 j_ J • this preparation tiie cell is promi- 

The lowest and smallest portion ^ent. in the more usual method 

of the brain stem is the medulla. ^^ staining, the fibres are more 

striknig and give the so-called 
Just below that is the spinal cord, spider cells. (From Huber, after 

the third of our main divisions, ^^^^ 
which extends about two- thirds the length of the spinal 
column. The position of these more prominent organs 
should be carefully studied in Figure 8. Superficially re- 
garded, the most striking differences between different 
structures are in the colors. The cortex, or outer layer of 
both cerebrum and cerebellum, is gray; the cord is white. 
The gray color is given by masses of cell bodies closely 
crowded together, while the white color is given by the 
white sheaths of the nerve fibres. Similarly, a section 
through any part of the central nervous system will show 
masses of white matter and other masses of gray matter. 
In the cord the centre is gray, the outer parts white; in 
the cerebrum the relation is reversed, but in each case the 



26 



FUNDAMENTALS OF PSYCHOLOGY 



Cer, 




Fig. 8. — The nervous system as a whole. On the left it is seen from^the side in 
position in the body; on the right exposed and seen from the front. Cer., the cere- 
brum; Cb., the cerebellum; Sp.C, the spinal cord; [iP, the pons; M, the medulla. 
The other letters designate nerve trunks going to the central nervous system and 
connections with the sympathetic system. (After Bougery.) 



DEVELOPMENT OF EMBRYO 27 

gray matter is a mass of cells, the white a mass of axones. 
Separate masses of cells are known as ganglia. 

The structures of the nervous system may also be 
grouped with reference to function. From this stand- 
point cells and fibres may be divided into sensory or affer- 
ent, associative or commissural, and motor or efferent. 
The sensory neurones are connected with sense organs, di- 
rectly or indirectly. The axones conduct from the periph- 
ery to the centre. The first cells of sensory ganglia are 
outside of the central nervous system, either in the sense 
organ, or in ganglia near the central nervous system, and 
their axones connect with other cells nearer the brain. The 
commissural cells and fibres transfer the impression from 
sensory cells to motor cells. The motor or efferent neu- 
rones stand in immediate connection with the muscles, or 
with neurones which serve to innervate the muscles, — are 
members of the chain that conducts impulses from the cen- 
tres outward. The neurones that possess these different 
functions cannot be distinguished structurally. The func- 
tions depend rather upon the connections in which the 
neurones are found than upon their structures. 

Development of Embryo. — To understand the struc- 
tural relations, one must go back to the development of 
the nervous system as a whole. Many relations, very 
complicated in the developed organism, are very simple in 
the earher stages. The complexities are caused by the con- 
ditions of growth. Our sketch of the development must 
be very brief, with many omissions, but even this may be 
helpful at some points. The complete adult is developed 
from an original cell, the fertilized ovum, by a process of 
division. The original cell divides into two, each of these 
into two, and so on. At first the derived cells are exactly 
like the original so far as can be made out. They are 



28 



FUNDAMENTALS OF PSYCHOLOGY 



grouped compactly. The first sign of differentiation comes 
when a hollow appears within the mass, and the enclosing 
cells divide into two layers, an outer, the ectoderm, and an 
inner, the entoderm. Soon a third intermediate layer 
develops from the others to constitute the mesoderm. 




Fig. 9. — Embryo of a rabbit at eight days to show the neural groove, rf is the 
neural groove; //, the region in which the fore-brain is to develop. (From Kolliker.) 

These layers may be distinguished throughout the remaining 
development and give rise to different parts of the organism. 
The entoderm gives rise to the inner wall of the internal 
organs, and to certain organs, as the liver and pancreas. 
From the mesoderm develop the supporting structures, 
connective tissue, bone, muscle, and the body of most of 



DEVELOPMENT OF THE NERVOUS SYSTEM 29 

the internal organs. The ectoderm develops into the skin 
and its appendages, the mucous membrane of the mouth 
and nose, and, what concerns us most, into the nervous 
system and the nervous parts of the sense organs. 

The Development of the Nervous System. — It is inter- 
esting to note how the outer layer of the embryo gives rise 

G 




Fig. 10. — Closing of the neural groove. The figure at the top shows the groove 
still open; in the next, the sides appro.ximate each other; in the lowest, the closure 
is complete. G, the cells from which the spinal ganglia develop,- a, the ectoderm; 
b, the epithelial lining of the medullary tube. 

to the nervous system which finally becomes embedded so 
deeply in the structure of the body. Very early in the 
embryonic Hfe, within the first two weeks, there appears 
upon the surface of the embryo a slight depression known 
as the neural groove (Fig. 9) . This gradually grows deeper, 
and finally the upper edges grow together and form the 



30 



FUNDAMENTALS OF PSYCHOLOGY 



neural tube (Fig. lo). From the walls of this tube the entire 
nervous system grows. The forward end becomes the 
brain, the other longer portion, the spinal cord. The cells 
that line the tube give off first masses of cells with radiating 
fibres that serve as a supporting structure or scaffold 




Fig. II. — The ependymal or supporting structure of the embryo cord. 
(From Cajal.) 

(Fig. 1 1) . Some at least of these develop later into neuroglia 
cells, the supporting tissue of the central nervous system. 
This first supporting structure takes the general form of 
and may be said to prepare the way for the truly nervous 
structure. After the supporting or ependymal structure is 
well developed, later divisions of the cells lining the tube 
give rise to embryo neurones or neuroblasts. These make 



DEVELOPMENT OF THE NERVOUS SYSTEM 31 




Fig. 12. — Epithelial cells lining the neural 
tube and germinal cells, A, that have developed 
from them. (From Cajal, alter His.) 



their way outward toward the position they are to occupy 
in the adult cord. As 
the neuroblasts develop 
they send out processes, 
axones and dendrites. 
The axones grow out- 
ward to the structures 
they are to supply. A 
section of the cord at the 
end of the first month 
shows a layer of epithe- 
lial cells about the cen- 
tral tube, farther out the 
neuroblasts and then the 
axones (Fig. 13). Every- 
where in the brain as well as here in the cord the principle 
holds that the processes are outgrowths of the cell bodies. 

The axones grow out 
from the cells up the cord 
to the higher centres, and 
on the ventral side in 
particular outward to the 
muscles, even to the re- 
mote parts of the body. 
Meanwhile the sensory 
neurones are developing 
in the dorsal ganglia. 
When the walls of the 
neural groove grow to- 
gether to form the tube, 

Fig. 13. — Schematic section of embryo ,• f +T-, + A 
cord. ^, anterior or motor root; B, posterior portions 01 tne eCtOQCrm 
root; C, central canal; a, epithelial wall; g^j-g cut off both from 
b, neuroblasts or embryo neurons; c, the pri- 
mordial white matter. (Cajal, after His.) the tube and frOm the 




32 



FUNDAMENTALS OF PSYCHOLOGY 



surface. They move away from the median plane, and are 
surrounded by mesoderm tissue. The original ectoderm 
cells give rise to neurones. At first the processes of the 




Fig. 14. — Development of dorsal root ganglion with cord. A, motor nerve; 
5, "posterior root, fibres from ganglion entering cord; E, 'T '-shaped cells of dorsal 
ganglion in their bipolar stage; e, sensory nerve, dendrites of 'T '-shaped ceUs. 
(From Cajal.) 

neurones grow out from either end; one goes outward to 
the end organ in skin and muscle, the other grows into the 
cord and sends fibres upward in the back part of the cord 
or into the central gray. Later in the development, the two 
processes grow together for a short distance from the cell 



ANTERIOR PORTION OF THE NEURAL TUBE ^3 



and then grow off at right angles to the original stem. They 
thus resemble a 'T,' and the cells are known as the 'T'- 
shaped cells. Before birth the germinal layer stops giving 
rise to new cells and forms a single layer of cells Kning the 
central tube. 

The Development of the Anterior Portion of the Neural 
Tube. — The growth of the forward end of the neural tube, 



Thalamus 



Corpora Quadrigemina 
Midbrain 




Forebrain 



Tweenbrain 



Fig. 15. — The five-vesicle stage of the human brain, giving names of vesicles: 
fore-brain, tween-brain, etc., and the parts of the adult brain that develop from 
each. (After His.) 

the part from which the brain develops, follows much the 
same plan. The supporting structure and the neuroblasts 
appear as in the cord. One difference should be emphasized, 
however, that the neuroblasts are projected farther from 
the tube and the axones grow inward and extend up or down 
within the masses of cells. In consequence the white matter 
is, for the most part, within; the gray, on the surface. One 
other problem upon which development throws considerable 




34 FUNDAMENTALS OF PSYCHOLOGY 

light is in the longitudinal arrangement of the parts. By 
the end of the second week, the forward end of the tube 
bends sharply downward, ventrally, and becomes divided 
into separate pouches or vesicles. At first three, later five, 
vesicles are to be seen. These are marked by constrictions 
in the tube at four places. Two most marked are just before 

and just behind the bend 
in the tube. The vesicle 
between is the mid-brain. 
The region in front is 
divided by a shallower 
groove into end-brain or 
fore-brain, and tween- 
brain, while the portion 

Fig. i6.- Development of brain vesicles j^g^ behind is similarly 

seen from above. The hemispheres may •' •' 

be seen growing from sides of fore-brain. divided iuto the hind- 

(From His.) , . jr. u • 

brain and after-bram. 
These early divisions give the name to the corresponding 
parts of the adult nervous system. The cerebrum develops 
from the fore-brain, the thalamus, and other parts from 
the tween-brain, the corpora quadrigemina and other struc- 
tures from the mid-brain, the cerebellum and pons from 
the hind-brain, and the medulla from the after-brain. In 
each the walls are very much thickened and at many 
points there are very large outgrowths, but all grow from 
the lining of the original tube by the process of cell divi- 
sion indicated above. The original cavity undergoes 
changes of shape in many places. It becomes much 
heightened in the hind-brain to constitute the fourth ven- 
tricle, in the mid-brain it retains its original shape, and 
continues small as the aqueduct of Sylvius. It broadens 
in the tween-brain to the third ventricle and bifurcates in 
the cerebral hemispheres to form the lateral or first and 



THE CEREBRUM 35 

second ventricles. Nevertheless it remains continuous 
throughout from the lateral ventricles in front to the 
bottom of the spinal cord. It is filled everywhere with the 
cerebro-spinal fluid. 

The Cerebrum. — The development of the cerebral 
hemispheres deserves special mention. They appear early 
as lateral swellings on the fore-brain. These grow first to 
the side, then upward and back until they cover mid-brain 





Fig. 17. — Shows development of the hemisphere, the left figure at three months, 
the right at six months, fs is the fissure of Sylvius; c, the cerebellum; m, the 
mid-brain. (From Kolliker.) 

and cerebellum, an outgrowth of the original hind-brain. 
The two hemispheres are distinct from the beginning. They 
merely come into contact along the median fissure; there 
is no organic connection between them except at the base. 
In this growth backward, the cerebral hemispheres are 
folded here and there, and these folds account for some of 
the permanent markings upon its surface. Most striking 
of these is the fissure of Sylvius. This can be seen from the 
second month. It develops in very much the same way as 
the median fissure from the growing together of two out- 
growths of the cerebral hemispheres. When these come into 



36 FUNDAMENTALS OF PSYCHOLOGY 

contact on the surface, they leave considerable portions ot 
their superficial areas in juxtaposition well below the surface. 
The walls of this deep fissure constitute the island of Reil. 

In the course of the development, then, we find neurones 
originating from the cells that lined the central tube. 
Masses of nerve cells in the cord constitute a continuous 
structure. In the cerebrum and cerebellum they show an 
exuberant growth in comparatively isolated regions, sepa- 
rated from other cell masses by regions of white matter. 
From these cells the axones grow out for long distances to 
the sense organs and to the muscles on the peripheral side 
and to the other cell masses in central structures, until 
sense organ is connected with muscle, and centre with centre 
throughout the organism. The problem of understanding 
the nervous system is very largely one of tracing these con- 
necting paths from sense organ to centre, and from centre 
to centre within the entire system. 

Important Facts of Nervous Conduction. — The function 
of a nerve unit is to conduct something which we call the 
nerve impulse from the end of the dendrite to the end-brush 
or muscle. The question at once arises, what is it that is 
conducted, what is the nature of the nerve impulse? Two 
answers have been suggested: one, that it is an electric 
current; the other, that it is similar to the burning of a train 
of gunpowder. Five experimentally determined facts must 
be considered before we can draw conclusions. 

1. The rate of the impulse in man is from loo to 
123 metres per second, according to Piper. This is so 
slow as to make it impossible to regard the nerve im- 
pulse as merely an electric current. 

2. The impulse is accompanied by relatively sKght 
fatigue. Nerves have been stimulated for several hours 
and will still conduct. 



THE NATURE OF THE NERVE IMPULSE 37 

3. It uses very little oxygen, although oxygen is 
required if the nerve is to conduct. 

4. Carbon dioxide is given off, but at a relatively 
slow rate. 

5. Only extremely small amounts of heat are pro- 
duced by the action of the nerve. 

These facts together indicate that the energy changes in 
conduction are relatively slight and would eliminate the 
possibihty that it is like the burning of a train of gun- 
powder. Important in any theory are the electrical changes 
which have been seen to accompany nervous action. Two 
currents are to be noticed: the current of rest and the 
current of action. Both may be measured by a galva- 
nometer which connects the cut end of a nerve with its side. 
When the nerve is not stimulated a current passes from the 
side to the cut end; when the nerve is excited the current 
passes in the opposite direction. The cut end is negative 
when at rest and positive when excited. More important 
are recent results which show that as an impulse passes 
along a nerve, the excited portion is always negatively 
charged as compared with the unexcited portion. This 
negative charge moves at the rate of the nerve impulse. 
These results show that while the nerve impulse is not 
identical with the electric current, electric currents are 
involved in the transmission of the nerve impulse. 

The Nature of the Nerve Impulse. — While the facts 
enumerated in the last paragraph ehminate the two most 
simple possibilities: that the nerve impulse is an electric 
current and that it is a transmission of a chemical change 
Hke that of the burning fuse, they show that both chemical 
and electrical phenomena are involved. The simplest pic- 
ture is that the nerve impulse involves both chemical and 
electrical processes, that it is excited by a chemical change 



38 FUNDAMENTALS OF PSYCHOLOGY 

which starts short electrical currents as does the chemical 
action in a battery. These electric currents in turn produce 
new chemical changes at a short distance which again give 
rise to currents. Many more details need to be supphed, 
but there is fairly general agreement that both chemical 
and electrical activities are involved in the nervous impulse. 
Like all chemical reactions these have electrical effects and 
accompaniments. The chemical changes are comparatively 
slight but suffice to induce the electric currents. Whatever 
the character of this nervous impulse, it constitutes the 
essential activity of the neurone, and as it travels from 
sense organ to centre or from centre to muscle, the processes 
of sensation or of movement are made possible. 

The Course of the Impulse. — The specific activities of 
the nervous system depend upon the course that the impulse 
takes through it. The simplest form of nervous response 
that an organism makes is called the reflex. It is the type 
of all nervous action. The winking of the eye, the with- 
drawal of the hand when burned, are primarily reflexes. 
The explanation of the reflex is to be found in the presence 
of chains of neurones between the sense organ excited and 
the muscle producing the response. The simplest reflex 
involves at least two groups of neurones, a sensory and a 
motor. It can be seen most clearly in the spinal cord. If 
a finger be pricked, an impulse passes to the cell body of a 
neurone in the spinal ganglion, thence along the axone to 
the motor cell in the front of the cord, whose activity causes 
the muscles of the arm to contract and draw back the hand. 
That these reflexes depend upon the nervous connections 
in the cord and upon these alone is evident from the fact 
that they persist in the lower animals after the cord has 
been cut off from the brain, but cease if the cord is destroyed 
or the nerves that lead to or away from it be severed. In a 



REFLEXES IN THE CORD 39 

frog, whose head has been removed or whose cord has been 
cut in its upper part, the reflexes persist. Stimulation of the 
skin causes movements of the members. Even a dog may 
be kept alive after its brain has been removed, and this 
'spinal dog,' as it is called, carries on the reflex activities of 
the lower body in a perfectly normal way. When stimulated 
on the skin of one foot, that foot will be drawn back. If 
the intensity of the stimulation be increased, the opposite 
member is moved, and as the stimulation is still further in- 
creased in intensity, movements up and down the trunk 
at many different levels will be made. In the frog, for 
example, if a bit of paper be dipped in acid and put upon 
the skin of the right thigh, the first effect is to bring the 
right foot up in an attempt to wipe away the paper; if that 
foot be held, the other will be brought across and remove 
the stimulation. 

The Spinal Coed 

Reflexes in the Cord. — To understand these reflexes 
as well as most of the activities of the lower part of the body 
it is necessary to sketch the structure of the spinal cord. 
The cord contains an inner mass of gray matter, somewhat 
Hke an H in shape when seen in cross section, surrounded by 
columns of white matter. The extensions of the gray matter 
are known as the horns; the backward extension, the dorsal 
horn, and the other, the ventral. The white matter between 
and around the horns comprises the columns. The dorsal 
horns receive axones from the spinal ganglia. The anterior 
horns contain large motor cells whose axones send impulses 
to all of the muscles. All acts, voluntary as well as reflex, 
are directly caused by the excitation of these cells. The 
white matter is divided by these horns into three columns, 
the dorsal, the lateral, and the ventral. In the simple 



40 



FUNDAMENTALS OF PSYCHOLOGY 



niN 



reflex the sensory impulse is received by the neurones in 
the dorsal root ganglion, thence is transmitted by their 
axones across the gray to excite the ventral horn cells, as may 

be seen in Figure i8. 
The sensory neurones 
also send collaterals to 
the ventral horn of the 
opposite side. These 
collaterals may con- 
nect directly with 
motor cells or they 
may come into contact 
with the dendrites of 
intermediate or com- 
missural neurones, 
whose axones make 
the connections with 
the anterior horn cells. 

Fig. 1 8. — Simple reflex connection in the 

cord, a, 'T '-shaped cell in the posterior root The pomts of COntact 

ganglion; .iV sensory neurone; A. dendrite or ^f ^^^^^^ ^^^ ^^^_ 
teledendrion of sense organ m skm; C^, motor 

cell, connecting by axone n with muscle M. dritCS are loiOWn aS 

(From Huber.) _,, . „, 

the synapses. Ihese 
offer resistance to the passage of the impulse, and synapses 
differ in the amount of resistance they offer. This differ- 
ence in resistance determines the course of the reflex. 
Thus the synapses to the motor neurones which excite the 
muscle of the side of the body stimulated are most perme- 
able, and in consequence the first and usual movement is 
made by the member on the same side. It is only when 
the stimulus becomes stronger that the member opposite 
moves. The neurones in the spinal ganglia also send col- 
laterals up and down in the cord, which connect directly or 
through commissural neurones with the motor neurones at 




REFLEXES IN THE CORD 




>f^4 ^\f f^ 



m 



^wwww^^ 




41 






&.C 






&.2 



■5 ° 



-^ 4 i^ ^ I 



^ 1 n 




«i =« s 

° r2 "S 



^ 't! O 



-a o ^ 
& c S 



7^. 









<J ?« 



(U->^'0 



H rt =1 



dS 



6 B 






e 

a o 



42 FUNDAMENTALS OF PSYCHOLOGY 

various levels (Fig. 19). These make possible reflex exci- 
tation of groups of muscles above and below the point of 
stimulation. These cord reflexes are all to be explained in 
terms of the connections between sensory and motor neu- 
rones. What the response shall be is determined by the de- 
gree of openness of the synapses between different neurones. 
Tracts in the Cord. — In addition to the reflex functions 
of the cord, it also serves as an important path of conduction 
between the periphery and the higher structures of the cen- 
tral nervous system, and between its own structures at dif- 
ferent levels. The conduction paths may be divided into 
sensory or afferent, and motor or eft'erent. The sensory 
fibres all come, directly or indirectly, from the dorsal roots 
and the spinal gangHa; the motor tracts all end in the cells 
of the ventral horn. The different tracts are to be distin- 
guished in terms of the higher centres to which they lead 
or from which they descend. The most important of the 
higher centres with which the cord connects are the cere- 
bellum, which receives ascending or sensory tracts and from 
which motor paths descend directly and by way of the red 
nucleus; the corpora quadrigemina, from which small 
tracts descend and to which they ascend; the thalamus, to 
which sensory fibres go on the way to the cerebral cortex; 
and the cortex itself, the outer layers of the cerebrum. 
From this descend two tracts, whose fibres carry voluntary 
impulses to the muscles of the body. Of the afferent tracts, 
the most easily made out are the columns of Goll and Bur- 
dach on the dorsal side. These occupy most of the region 
between the dorsal horns. The column of Goll is nearer 
the centre, the column of Burdach more lateral. Each is 
composed of fibres from the spinal gangHa, axones of 
neurones in the ganglia. The only difference is that the 
more lateral fibres come from parts of the body on approxi- 



TRACTS IN THE CORD 



43 



mately the same level, which have just entered the cord; 
the more central have entered lower down and have been 
crowded toward the centre by those that come in later. 
Both groups of fibres end in the medulla and there make 
connections with neurones which send impulses to the 



Ascending {Centripetal) Tracts. 
l=Long fibres of the posterior 
roots. 

1] =Spino-cerebeUar tracts (a, dor- 
sal ; 6, ventral = tract of 
Gowera). 

lII=Spiuo-thalamio tract. 



Descending (Cmlrijutjal) Tracts. 
l = Cortico-3pmal tracts (a, lateral 

pyramid tract ; 6, anterior 

pyramid tract). 
2-5 = Subcortico-spinal tracts (2, 

rubro-spinal and thalamo- 

spinal ; 3, vestibule- spinal ; 

4, tecto-apinal). 

5. Descendint; 
fibres of the 
dorsal column. 




TOPOQEArHY OF THE LONQ SPIUAL TEACTS. 

Fig. 20.— Paths of conduction in cord. (From Bing's "Compendium of Regional 
Diagnosis." Published by Rebman Bros., New York.) 

thalamus and thence to the cortex. Their chief function 
is to transmit impulses from the muscles. In the same area 
is the so-called 'comma' tract, named from its shape, which 
consists of collaterals from entering neurones that turn 
downward to connect with motor cells lower in the cord. 

Other well-marked afferent tracts are found on the lateral 
border of the cord, the cerebellar tracts. They are divided 
into two, the more dorsal tract of Flechsig and the more ven- 



44 FUNDAMENTALS OF PSYCHOLOGY 

tral tract of Gowers. Both are derived from cells in the 
dorsal gray of the cord and carry impulses to the cerebellum. 
Still another sensory tract of importance lies within Gowers' 
tract. It is marked spino-thalamic in Figure 20 and con- 
stitutes part of the pathway from the skin to the cortex. 
Sensory impulses from the skin are carried by axones from 
the 'T'-shaped cells in the spinal root ganglia into the gray 
of the cord. There they connect with a second set of neu- 
rones whose cell-bodies he near the spinal canal. The axones 
from these cells cross and in part go up this spino-thalamic 
tract to the thalamus and thence to the cortex. The tract 
may also contain some fibres leading to the corpora quadri- 
gemina. 

Motor Tracts. — Of the descending or motor fibres the 
most important are found in the pyramidal tracts. There 
are two pyramidal tracts, the crossed and the uncrossed. 
The former, always the larger, lies just inside the Flechsig 
tract and is very close to the dorsal horn of gray matter. 
The uncrossed pyramidal tract lines the ventral fissure of 
the cord. Both tracts are composed of axones of cells in 
the cerebrum, which descend to make connection with the 
anterior horn cells. They carry the voluntary impulses. 
The first mentioned is composed of fibres that cross in the 
medulla; the second or anterior, of fibres that have con- 
tinued down on the same side but cross in the cord near the 
level of the cells with which they connect. Other bundles 
descend from the cerebellum. One, coming by way of the 
red nucleus, the rubro-spinal (Fig. 20), lies ventral to the 
lateral pyramids; the other is on the ventral border. 
Mention should also be made of a bundle from the corpora 
quadrigemina, the tecto-spinal, on the ventral border of 
the anterior horn. It should be noted that the names ap- 
plied in each instance indicate the structures connected : the 



MOTOR TRACTS 45 

cortico-spinal tract connects cortex with cord; spino- thala- 
mic, cord with the thalamus, etc. 

In addition to these long bundles running from cells at 
one level to others above and below, there are many fibres 
which make possible the transfer of impulses within the 




Fig. 21. — Series of sections of the cord to indicate difference in the amount of 
white and gray and the relative size of the cord at the different levels. 5 is a sec- 
tion through the lumbar enlargement, where the nerves of the legs enter and leave; 
D, a section through the cervical enlargement which supplies the arms. This figure, 
together with figures 23, 24, 25, and 31, was drawn by Mr. Atwell of the Anatomical 
Laboratory of the University of Michigan. 

cord. These are numerous at the borders of the gray matter, 
but also occupy parts of the white area that have been as- 
signed no other function in the above discussion. Probably 
some of the sensory impressions pass along these fibres on 
their way to the brain. They go from neurone to neurone, 
into the central gray and out again, instead of taking the 
more direct course provided by the long fibres. It should 
be added that the arrangement of fibres is different at 
different levels. The pyramidal tracts, for example, are 



46 FUNDAMENTALS OF PSYCHOLOGY 

much larger in the upper portions of the cord, as some of 
the fibres that appear at the upper level leave it to make 
connections with the ventral horn cells. In fact, the ventral 
tract cannot be made out at all in the lower regions. The 
relative amount of white and gray matter also varies at 
different levels. The gray matter has the greatest extent 
in the lower lumbar region and in the cervical region, where 
the large nerves for the legs and arms enter and emerge. 
The cord as a whole also increases in cross section from 
below upward, with marked swellings where the large nerves 
enter. See Figure 21. 

The Brain Stem 

Functions of the Brain Stem. — In the brain stem, from 
the medulla upward, the structure of the nervous system 
becomes much more complicated, but the functions and 
general arrangements are much the same. We may dis- 
tinguish three functions of the structures in the brain stem : 

1. Fibres massed in well-defined tracts carry the 
sensory impressions upward and motor impulses down- 
ward between cord and cerebrum. 

2. Masses of neurones care for the reflexes of the 
head in very much the same way that the cord cares 
for those of the body. Nerves lead into them from 
the special sense organs and from the skin of the head, 
and motor nerves lead out from them to the muscles 
of the head just as sensory nerves lead into, and motor 
nerves go out from, the cord. 

3. The brain stem also makes wider interconnec- 
tions, — serves to combine large numbers of sensory 
stimuli from different sense organs and to combine and 
distribute them in exciting muscles in widely scattered 
parts of the body to make harmonious movements. 



STRUCTURES IN THE BRAIN STEM 47 



Making the different parts of the body work together 
is the peculiar function of the nervous system. The coor- 
dinations in the brain stem are wider than those in the 
cord and those of the cerebrum are widest of all. 

Important Structures in the Brain Stem. — To trace the 
ascending and descending paths of impressions, we need to 
distinguish several 
structures in the 
brain stem that 
serve as way sta- 
tions, points where 
impulses are trans- 
ferred from the 
axone of a lower 
neurone to the 
dendrites of a neu- 
rone that carries 
them upward, or 
where descending 
impulses are inter- 
rupted and trans- 
ferred to new neu- 
rones. The first 
are in the medulla, 
the so-called nuclei 
of GoU and Bur- 
dach (Figs. 23, 24). These, with the thalamus, are parts 
of the pathway of sensory impulses from the trunk and 
Hmbs. The thalamus is a structure at the base of the 
cerebrum which can be seen in a median section of the 
nervous system on the walls of the third ventricle, or from 
above in Figure 22. Below it to one side may be seen the 
internal and external geniculate bodies, and still lower lie 




Fig. 22. — Dorsal view of brain stem, fg, column 
of GoU; Jc, column of Burdach; n, anterior, /, posterior 
pair of corpora quadrigemina; th, thalamus; k, external 
and k' internal geniculate bodies; x, epiphysis (pineal 
gland); ps, pyn, pi, are superior, middle, and inferior 
peduncles of the cerebellum, which may itself be seen, 
in part cut away and drawn to one side. (From 
Wundt.) 



48 



FUNDAMENTALS OF PSYCHOLOGY 



the corpora quadrigemina. These are both receiving organs 
for certain of the fibres from eye and ear, and will be men- 
tioned in connection with these sense organs. The red 
nucleus lies within the body of the brain stem below the 
back portion of the thalamus and the corpora quadrigemina 
(Fig. 31). This is a way station from the cerebellum and 
also from the cortex to the cord. A part of the cerebellum 
can be seen drawn to one side in Figure 2 2 and the pons is 

Column of GoU 
Column of, 
Burdach 




Fig. 23. 



■ Section of the medulla to show the crossing of the pyramidal tracts, a 
section a little below that shown in Figure 24. X 4- 



directly in front of it. For our purposes these are the most 
important structures in the brain stem. 

The Paths in the Brain Stem 

The Paths between Cord and Cortex. — Nerve currents 
from the sense organs of the limbs and trunk may reach 
the cortex by two distinct paths. The first, which probably 
carries only the impulses from the muscles and other deeper 
lying tissues, is provided by the columns of Goll and Bur- 
dach. Axones of cell bodies in the spinal gangha ascend 
b}'' these tracts to the nuclei of Goll and Burdach. Here 
they come into contact with dendrites of other neurones 



THE PATHS BETWEEN CORD AND CORTEX 49 

whose axones cross to the other side and then proceed up 
the central portion of the brain stem to the thalamus. 
Thence a third set of neurones carries the impulse to the 
cortex. Impulses from the external skin apparently travel 
by other spinal neurones whose axones enter the central 
gray of the cord and make connections with dendrites of a 
second neurone whose cell body lies near the central canal. 



Column of GoU 
Column of, 
Burdach 



Nucleus of GoU 




Pyramids 

Fig. 24. — Section through the medulla to show the crossing of the sensory fibres, 
the axones of cells in the nuclei of GoU and Burdach. X 4. 

These neurones send their axones up the lateral column of 
the opposite side to the thalamus. The exact path that is 
followed in the lateral column is not definitely agreed upon. 
Some authors believe that there is a long tract in the an- 
terior portion of the lateral column, the spino-thalamic 
tract in Figure 20; others that the path goes by way of 
short fibres near the gray and perhaps may be- interrupted 
at different levels. The axone may reenter the central 
gray several times, connect with a new neurone, and have 
that neurone continue the impulse upward. That there is 



50 FUNDAMENTALS OF PSYCHOLOGY 

a pathway upward on the side of the cord opposite to that 
of the sensory nerve stimulated, and that this carries the 
cutaneous impulses, is made very probable by observ^ation 
of pathological cases. Figure 26 shows the posterior paths. 
The descending tracts from the cerebrum are the pyramidal 
tracts. The fibres that compose them are axones of cells 
in the motor cortex. They can be traced on the anterior 



FiUet 




Transverse pon 
tine fibres 

Fig. 25. — Section through pons. The interlacing of the descending pyramidal 
tracts, with the cross fibres of the pons, mainly connecting the lobes of the cere- 
bellum, is clearly shown. Above, dorsal to the pons, may be seen the section of 
the fillet, the sensory fibres ascending from the nuclei in the medulla to the thala- 
mus. A section of part of the fifth nerve may also be seen. 

portion of the brain stem through their whole course except 
where they intermingle with the fibres of the pons, as can 
be seen in Figure 25 (a section through the pons). In the 
medulla, part of the fibres cross, as can be seen in the 
cross section. Figure 23. These constitute the crossed pyra- 
midal tracts already noticed in the cord. The uncrossed 
pyramidal tract, which is usually smaller, and may not be 
present at all, continues down the anterior column and 
crosses in the cord at the level of the anterior horn cells 



NERVES AND THEIR CONNECTIONS 



SI 



with which it is to make connection. The right hemisphere 
of the cortex therefore always arouses movements in the 
left half of the body, 
and vice versa. The 
course of these de- 
scending fibres also can 
be seen in Figure 26. 
Only two neurones are 
required to transmit 
the motor impulse 
from the cortex to the 
muscle, while three at 
least are concerned in 
carrying the sensory 
impulse upward. 

Roots of Cranial 
Nerves and their Cen- 
tral Connections. — 
The brain stem is hke 
the cord, also, in its 
second set of 
functions, re- 
ceiving sensory 
fibres and im- 
pressions, and 
sending out 
motor nerves 
and impulses. 
Unlike the con- 
tinuous series of 
cells in the cord, 
the cell bodies 
whose dendrites 




Fig. 26. — Showing schematidlly the ascending and 
descending tracts between cord and cortex. A, pyramidal 
tracts; B, motor cell; C, D, sensory cells; E, F, nuclei of 
Burdach and of Goll; G, central sensory path; H, thal- 
amus. Only the sensory path by the posterior columns 
is indicated. The arrows indicate the direction of the 
impulse. (From Cajal.) 



52 



FUNDAMENTALS OF PSYCHOLOGY 



and axones constitute the so-called cranial nerves are 
grouped in isolated masses of cells along the brain stem, 
the nuclei of the cranial nerves. From these nuclei, con- 
nections are made with each other, with the cerebellum, 




Fig. 27. — The central connections of the cochlear branch of the eighth nerve, 
the nerve of hearing. The first layer of neurones have their cell bodies in the 
spiral ganglia (VIII c) which correspond to the spinal root ganglia of the cord. 
Their axones connect with a second layer of neurones either in the ventral root of 
the eighth nerve (na) or in the tuberculum acusticum. The axones from this sec- 
ond layer of cells in both nuclei go to the superior olives (os), some to the one on 
the same side and some to the one on the opposite side. From the olives third 
neurones connect with a fourth layer of neurones with cells in the nucleus lemnis- 
cus lateralis {nil) which carry the impulses to the internal geniculate bodies {cgm) 
and thence by a fifcn layer to the temporal lobe of the cerebrum. Certain of the 
neurones in the olives send axones to the inferior corpora quadrigemina {colliculus 
inf.) where reflex connections are made with motor roots of the brain stem. (From 
Rauber-Kopsch.) 

corpora quadrigemina, and cortex. The location and con- 
nection of the parts would require more space and the 
knowledge of more details of anatomy than can be given 
in so brief a treatment. It may be said in general that 
there is some approximation to the arrangement of the 



THE OPTIC AND CUTANEOUS TRACTS 53 

spinal cord in that the motor nerves frequently are anterior 
to the ventricles, while the sensory roots are more lateral 
or posterior. These sensory and motor nuclei also have 
connections with the cortex similar to those of the cord. 

Connections of the Auditory Nerve. — We may trace 
the course to the cortex of some of the more important 
sensory nerves of the head. The eighth nerve, or nerve of 
hearing, consists of the axones from the cells in the spiral 
ganglia in the ear (Fig. 27). These connect with the 
dendrites of cells in the root of the eighth nerve at the 
level of the pons; from these, new neurones carry the im- 
pulse to the superior olives on both sides, and thence by 
two other neurones it goes forward to the internal or me- 
dian geniculate body, a body near the thalamus, and to 
the posterior corpora quadrigemina. From the geniculate 
body, one set of neurones carries the impression forward 
to the cortex where hearing takes place. In the posterior 
corpora quadrigemina reflex connections are made with ear 
and head muscles. 

The Optic and Cutaneous Tracts. — The optic tract is 
very similar (Fig. 28). The axones from the eye enter 
the external geniculate body and possibly the visual area of 
the thalamus, thence go to the cortex. The fibres that 
control the eye reflexes and the higher coordinations run 
directly to the anterior corpora quadrigemina, where they 
make connections with nuclei of the motor nerves to the 
eye. The fifth nerve, in part a sensory nerve for impres- 
sions from the skin and other tissues of the head, has its 
cells in a large ganglion, which has much the same relation 
to the brain stem that the dorsal root ganglia have to the 
cord. Thence axones connect with second neurones in the 
nucleus whose axones go to the thalamus, whence the third 
neurone makes connection with the cortex (Fig. 29). In 



54 



FUNDAMENTALS OF PSYCHOLOGY 



general the fibres of all these nerves cross either in the 
brain stem or, in the case of the eye, whose fibres cross in 
part only, in the optic nerve itself. The fibres from the 




Corpus ^ 
Geniculatum lat.*'- 



FiG. 28. — The central connections of the optic nerve. From the neurones in the 
eye the axones that form the optic nerve extend, after partial crossing in the chi- 
asma, to the external geniculate body where connection is made with a second 
series of neurones which carry the impulse to the median surface of the occipital 
lobe. Other axones connect with the pulvinar of the thalamus and with the anterior 
corpora quadrigemina {Colliculns sup.). From the latter impulses are carried to 
the roots of the oculo-motor nerves by the path fa, through which reflexes are 
aroused. (After Bechterew.) 




Fig. 29. — The ascending or sensory connections of the fifth nerve. The rela- 
tions are very similar to those of the dorsal roots of the cord. The receiving neu- 
rones have cells in the ganghon {Ganglion V), send axones to the sensory nuclei, Vs, 
which correspond to the nuclei of Goll and Burdach for the spinal nerves, whence 
the new neurones connect with a third layer of neurones whose cell bodies are in 
the thalamus and which carry the impulse to the cortex. (From Rauber-Kopsch.) 

55 



56 



FUNDAMENTALS OF PSYCHOLOGY 



inner halves of the retinas cross, and finally reach the cor- 
tex on the opposite side; those from the outer halves go to 
the cortex on the same side. Corresponding to the py- 
ramidal fibres that descend to the cord, motor fibres also 
descend from the cortex to the roots of the motor nerves 
of the head and make possible the voluntary control of the 
eyes, tongue, facial muscles, etc. 



uasseriuTL 
Canqlion,. 



Ophtkaltrtie branck ofSt^. Lonj cili'ari/ nerues. 
u r . ^-^ \^DilaIor 

■Sfihitveter 
jou/oillae. 



Superior Cemealj' 




(Vhinal 
Cord. 



Ciliary Canclioru '^korl Ciliary Tierccs 



Cervical 
(VjmpaVietie 



Fig. 30. — The reflex control of the size of the pupil. The impulse of dilatation 
takes the long path from the corpora quadrigemina down to the cord and back 
through the cervical sympathetic, the superior cervical ganglion, and out through 
a branch of the fifth nerve to the iris. The impulse to contraction makes connec- 
tion through the third nerve with the ciliary ganglion, thence to the iris. (From 
Howell's "Physiology," after Schultz.) 

The reflex function may be illustrated by the contrac- 
tion of the pupil in a bright Hght. As was said above, the 
optic nerve sends one branch to the anterior corpora quad- 
rigemina. Thence axones proceed to the roots of the third 
nerve. Neurones there in turn connect with the ciliary 
gangHon back of the eye, which sends the impulse to the 
circular muscle in the iris. Strong hght causes the sensory 
impulse to ascend to the corpora quadrigemina, whence it 
is transmitted by a new neurone to the motor nucleus, 



THE FUNCTION OF THE CEREBELLUM 57 

thence, through at least two more neurones, to the muscle 
of the iris, whose contraction diminishes the diameter of 
the pupil (Fig. 30). Similar reflexes are seen in sneezing, 
which involves the spinal cord as well as the brain stem; 
in making a wry face at a bad taste, etc. In the medulla 
are the reflex centres that control respiration, circulation, 
and other vital functions. The details of the paths, so far 
as known, may be obtained from any good physiology. 

Cerebellum, Corpora Quadrigemina, and Thalamus 

Connections of the Cerebellum. — The third or coor- 
dinating function is most highly developed in the cerebel- 
lum and corpora quadrigemina. If we consider the con- 
nections of the cerebellum, it becomes evident that it is 
closely connected with the adjustment of movements. To 
it, as we have seen, go two sensory tracts from the cord. 
To it also go fibres from the vestibule of the ear, the organ 
for appreciating the position of the body as a whole. It 
receives fibres from the cortex and fibres from the ocular 
tracts. From it go fibres to the spinal cord directly and 
by way of the red nucleus in the mid-brain just below the 
corpora quadrigemina. It also sends fibres to the motor 
nuclei of the eye muscles. These make possible the move- 
ments of the muscles of the trunk and head. 

The Function of the Cerebellum. — The general func- 
tion of the cerebellum is to coordinate muscular move- 
ments, particularly those involved in keeping the balance. 
The influence is best evidenced by the defects that appear 
when the cerebellum is injured. Then the body is held 
erect only with difficulty, if at all, the movements are jerky, 
the patient staggers when walking, the gait is like that of 
the drunken man. The balance of the body is not ad- 
justed to the movements of the legs, the patient may lean 



58 



FUNDAMENTALS OF PSYCHOLOGY 



too far forward or too far back for the immediate position 
of the body. Recent work makes it probable that certain 
parts of the cortex of the cerebellum take care of definite 
parts of the body. Streeter has established the localization 
by tracing the fibres, Barany by a study of the effects of 
injuries of the cerebellar cortex and by direct stimulation 
of its surface. It is probable that the nerve currents from 

Anterior Corpora Quadrigemina 

Internal Geniculate buuy 




Cerebral Peduncles 



Red Nucleus 
Oculo-Motor Nerves 



Fig. 31. — Section of mid-brain to show position of red nucleus. The anterior 
corpora quadrigemina and the internal geniculate bodies can also be seen, as can 
the fibres of the third nerve, whose roots receive fibres from the corpora quadri- 
gemina on the way to the eye muscles. In the lower anterior portion the descending 
fibres that constitute the cerebral peduncles may be seen. The pyramidal tracts are 
in the median portion of this structure. X 2. 



the various organs, skin, muscle, the vestibules of the ears 
and the eyes, which give a knowledge of position, are here 
united and coordinated and then sent out to the muscles, 
where they produce the muscular contractions that keep 
the balance. The cerebellum thus serves to bring together 
the sensory impressions concerned in movement, to gradu- 
ate them properly, and to send out impulses which shall 
control the lower reflexes, check some, increase others, and 
make all work together in proper balance. 



THE FUNCTIONS OF THE THALAMUS 59 

Functions of Corpora Quadrigemina. — From the fact 
that the corpora quadrigemina receive fibres from skin, 
ear, and eye, and have connections with the motor cells in 
the cord, as well as with the eye muscles and other muscles 
of the head, it seems probable that this may be a similar 
coordinating centre. In the lower animals the large devel- 
opment of these organs, as compared with the other re- 
gions of the brain, together with direct experiment, make 
it seem likely that many of the automatic movements are 
coordinated here. In man, however, this lower centre of 
coordination has been largely overshadowed in its func- 
tions by the cerebral hemispheres, so that it plays a sub- 
ordinate part. It is the centre for reflexes of the eyes, and 
probably for movements of the head, but neither experi- 
ment nor pathology gives much evidence of a coordinating 
function. 

The Functions of the Thalamus, — We have seen that 
the thalamus is a way station for impulses from the skin 
and other sense organs in their course to the cortex. Re- 
cently evidence has been accumulating that it is also 
closely connected with emotional expression. In emotion 
there are changes in the circulation, in the expression of the 
face, and the secretions in certain of the glands. These 
responses seem to be produced reflexly through the thala- 
mus. When the thalamus is injured the responses are 
changed. Bechterew reports a case in which injury to one 
thalamus destroyed the emotional expression of one side 
of the face and left the other undisturbed. 

REFERENCES 
Villiger: Brain and Cord. 
Herrick: Introduction to Neurology. 
Howell: Physiology, Chs. VI," VII, VIIL 
Starling: Physiology, Ch. VII, §§ vii-xvi. 



CHAPTER III 

THE NERVOUS SYSTEM {Continued) 

In the cerebral hemispheres we come much closer to the 
problems that primarily concern psychology. Here, we 
believe, the processes which accompany consciousness in 
all its forms have their place, and run their course. But 
for an understanding of the nervous operations themselves 
this makes no difference. The structures and their func- 
tions can be best understood on the analogy of the lower 
parts of the nervous system. It is in its turn just a mass of 
neurones with their processes, and its functions can be 
represented as due to the spreading of impulses along paths 
within it. The problems that meet us here are those that 
have met us all the way up to this point. The cerebrum 
constitutes part of the highest and most compHcated path 
by which sensory impressions may pass over to the muscles 
and excite muscular contraction. 

The Functions of the Cerebrum 

The Parts of the Cerebrum. — In the cerebrum may be 
distinguished three sets of structures. On the surface there 
is a relatively thin layer of gray matter, a number of layers 
of neurones with connecting processes, — the cortex. This 
outer coat has a large surface because of the great number 
of fissures and folds that are found on its surface. These are 
much more developed in man than in the animals. Below 
the cortical gray the interior is largely filled with white 
matter, — masses of fibres that run from the cortex down- 

60 



LOBES OF THE CEREBRUM 6i 

ward to the brain stem, from one part of the hemisphere to 
another, or from one cortex to the other through the corpus 
callosum and the commissures. At the base of the cerebrum 
are found other masses of gray matter, the corpora striata. 
These are divided into a number of masses by the fibres 
that descend from the cortex to the brain stem, the corona 
radiata. The function of the gangha at the base of the cere- 
brum has not been definitely determined. They have con- 
nections with the centres in the brain stem, but relatively 
few with the cortex. It has been supposed that they have 
something to do with the regulation of the temperature 
of the body. We need not consider them farther. 

Lobes of the Cerebrum. — The cerebrum is divided by 
the median fissure into two hemispheres. Each hemisphere 
for convenience of reference has been divided into five lobes. 
Three fissures in the cortex have been selected as boundaries. 
The most prominent is the fissure of Sylvius. It is on the 
side of the cerebrum and runs backward and upward from 
a point under the skull on a level with the eyebrows. Al- 
though the edges of this fissure are in contact, there is usu- 
ally a considerable hollow below the surface, and its sides 
and bottom have a considerable area. This area is called 
the island of Reil and is usually spoken of as one of the five 
lobes. From a point near the middle of the Sylvian fissure, 
a second prominent fissure extends upward and a Kttle 
backward to the median fissure and often shows on the me- 
dian surface of the hemispheres. It never extends quite to 
the fissure of Sylvius, but is separated from it by a fold or 
gyre. The fissure itself is the central fissure, or fissure of 
Rolando. The central fissure marks off the frontal lobe 
from the parietal behind it, and the Sylvian fissure separates 
the frontal and parietal from the temporal lobes. The 
parietal lobe is bounded at the back by the occipital lobe. 



62 



FUNDAMENTALS OF PSYCHOLOGY 



The line of division is distinct on the median surface of the 
cerebrum, the so-called parieto-occipital fissure, but no 
boundary is to be noted on the lateral surface. The line 
of demarcation between the parietal and temporal lobes 

C R M 




Fig. 32. — Localization of cerebral functions. The figure above shows the outer 
surface of the right hemisphere; the one on p. 63, the mesial surface of the left 
hemisphere. In both figures the motor areas are marked by horizontal shading, the 
sensory by vertical shading, while the associatory areas are unshaded. The doubt- 
ful or partially sensory and motor areas are dotted. 5 is opposite the fissure of 
Sylvius; R, above the fissure of Rolando. On the mesial surface the parieto-oc- 
cipital fissure is just above the shaded portion marked V; M is above the motor 

is a line continuing the Sylvian fissure. It should be stated 
that the fissures and gyres are not the same on different 
brains. The Sylvian fissure can be recognized in every case, 
the central fissure in practically every case, but the others 
are subject to considerable variation. The five lobes, the 
frontal, temporal, parietal, and occipital, together with the 
island of Reil, are the parts into which the cerebrum is 



LOBES OF THE CEREBRUM 



63 



divided. The two important reference lines are the fissures 
of Sylvius and Rolando. They can all be made out in the 
diagram (Fig. 32). 

While the functions of the cerebrum stand in closest con- 
nection with thought and with mental operations in general, 
the development of a knowledge of the exact connection 



C R 




area; C, above the cutaneous and kinaesthetic area; V indicates the visual area; 
is below the olfactory area. The auditory area is just below the fissure of Sylvius, 
above H. FA designates the frontal, PA , the parietal, and TA , the temporal asso- 
ciation areas. There is some evidence that the dotted areas about the sensory and 
motor areas are areas in which particular associations are formed for the corre- 
sponding sense or movements. (The diagram embodies the results of A. W. Camp- 
bell, but has been modified in one or two respects to agree with the results of Flech- 
sig and Gushing.) 



between the parts of the cerebrum and mental action has 
been a matter of very slow growth. The phrenologists, 
Gall and Spurzheim, began it, but their methods were very 
inaccurate and their conclusions so much mixed with specu- 
lation that hardly any progress was made. After their time, 
in the third decade of the last century, through the work of 



64 FUNDAMENTALS OF PSYCHOLOGY 

Flourens, the opinion became fully established that the 
cerebrum acted as a unit, and no function could be assigned 
to one part rather than another. It was not until 1867 that 
Broca's studies of aphasia gave a suggestion that each part 
of the cortex has a special function, and led to studies of 
locahzation. Since 1890 the localization has been generally 
accepted. The only problem has been to determine how 
far the different parts interact in a given function. 

Methods of Studying Localization of Function. — The 
methods that have thrown light upon the subject fall in 
general under three heads, — experiment, observation of 
the effects of disease, and study of the paths and anatomical 
structure of the different regions. Experiments were early 
performed on the lower animals, in particular upon monkeys 
and apes, whose brains most nearly approach those of man 
in structure. Parts of the brain were extirpated, and when 
the animal had recovered from the shock of the operation, 
its movements were studied to see what change the opera- 
tion had made. Again the brains of animals were exposed 
and the cortex stimulated by electric currents and the re- 
sulting movements were noted. In man, cases of mental 
defects, whether sensory or motor in character, were 
studied carefully and then the brain of the patient examined 
after death and the two series of results brought into con- 
nection with each other. It was found, for example, that 
a man who showed one sort of difficulty in speech would 
have lesions in one part of the brain, a man with another 
sort of defect would have another area diseased. Careful 
study of many cases has shown that there is a close relation 
between the two. The anatomical methods have resulted 
in tracing paths of connection between many areas, and 
have shown some relations that could not be demonstrated 
by either of the others. One method of this character that 



THE MOTOR AREAS 65 

has given noteworthy results was introduced by Flechsig. 
He found that the different connecting paths in the brain 
became medullated successively as the nervous system 
developed, and by a method of staining brains at different 
ages, he was able to make one path stand out clearly among 
all of the others and to follow its connections with ease and 
certainty. Even more recently study of the cells, and of the 
arrangement of cells and fibres that make up different areas, 
has shown that areas which differ in function differ also in 
their finer structure. 

As a result of these methods, we feel assured that the 
cortex is the part in which the final coordinations take 
place and which is most closely related to consciousness. 
We may also assert that the cortex constitutes part of one 
of the paths, by which sensations may be brought into 
connections with movements. Since the brain makes pos- 
sible movement when a sense organ is stimulated, certain 
parts of the cortex must receive axones of sensory neurones, 
others must send axones down to the muscles. Fibres have 
been traced to the cerebrum from sense organs, and from 
the cerebrum to the motor cells, and so to the muscles. 
The first problem is to determine these sensory and motor 
areas. One may picture the sense organs and muscles as 
projected upon the cortex. The areas that receive sensory 
excitations and send out motor impulses are known as the 
projection areas. Other areas have been shown to be con- 
nected with these, to have fibres leading to and from pro- 
jection areas. These are known as association areas. 

The Motor Areas. — The motor areas are most definitely 
determined. They are in the frontal lobe just in front of 
the central fissure, extending from near the fissure of Sylvius 
upward to the median fissure and over on to the median 
surface. The muscles of the head and face are representee^ 



66 FUNDAMENTALS OF PSYCHOLOGY 

upon the lower portion, the areas for the arms, the legs, and 
the trunk are found in order as one proceeds upward. 
Since the descending fibres cross, the right half of the body 
is controlled from the left brain, and vice versa. The details 
can be made out with greater accuracy from the diagram 
than from any description. Some of the movements can be 
locaHzed with great definiteness. The thumb has a separate 
area for the control of its movement, and the same may be 
said of other important organs and muscles. These areas 
have been determined, in part by a study of the paralysis 
that comes with disease and in part by noting the move- 
ments that result from stimulating different portions of 
the motor cortex in animals. Then, too, in the motor areas 
are certain peculiar cells, the giant pyramidal cells, whose 
axones can be traced down the brain stem and cord as the 
pyramidal tracts. Most important of all is the fact that it 
is possible to stimulate the motor cortex of a man whose 
skull has been opened for examination. In a very striking 
operation by Dr. Gushing, the skull was opened over a large 
area during primary anaesthesia, then the patient was 
permitted to return to consciousness and the cortex stimu- 
lated while he was in a condition to report on what hap- 
pened. The results obtained in this way were sufficient to 
convince the world of science that the motor part of the 
cortex is restricted to the frontal lobe rather than extending 
backward across the central fissure, as was thought a few 
years before. 

The Sensory Areas. — The sensory areas are widely dis- 
tributed. The area for touch is found in the parietal lobe 
just behind the central fissure. The definite localization of 
parts of the body has not been determined as it has for 
movement. In fact, the opinion is still held in certain 
quarters that movement sensations alone — impressions 



THE SENSORY AREAS 67 

received from sense organs in muscle and tendon — have 
their seat in this region, while the skin senses proper are 
found elsewhere, but the upholders of this theory assign 
them to no definite place. Tracing paths and observation 
of injuries both coincide in giving this area to touch, what- 
ever the final definition of that term may be. The auditory 
area has been located in the posterior portion of the tem- 
poral lobe, in the convolution adjoining the fissure of Syl- 
vius, and probably extending over upon the wall of that 
fissure, the Island of Reil. Even more accurately deter- 
mined is the region for vision. This is found primarily in 
the calcarine fissure on the occipital portion of the median 
surface of the hemispheres. It has been located, on the 
basis of examination of the brains of cases of cerebral blind- 
ness, by tracing fibres from the optic tracts to it, and by 
examination of the brains of individuals blind from birth 
or early childhood. Donaldson found, for example, that 
the brain of Laura Bridgman was quite undeveloped in this 
region. The partial crossing of the fibres between the eye 
and the brain has been very definitely made out. If the 
right occipital lobe has been injured, the patient is found 
to be blind in the right half of both retinas, while the left 
halves retain their vision. Each fovea, or central point of 
clearest vision, seems to be represented on both hemispheres. 
Apparently, too, the posterior part of this area for vision 
receives impressions from the lower parts of the retinas, 
while the anterior portion receives its fibres from the upper 
retinas. Smell, and particularly taste, are least well 
localized. This is primarily due to the fact that a patient 
may suffer from considerable defects in either sense without 
great inconvenience, and in consequence is less hkely to 
complain and be carefully studied. Paths have been 
traced, however, from the olfactory nerve to the extreme 



68 FUNDAMENTALS OF PSYCHOLOGY 

tip of the temporal lobe, the hippocamp. This region, too, 
is the analogue of the portion of the cerebrum that is well 
developed in the lower . forms that show greater capacity 
for smell, so that aU that we know points to it as the cortical 
seat of the olfactory sense. Taste is supposed to be some- 
where in the same region, but the evidence is even less 
certain than for smell. Each of these areas can be better 
made out from the diagram (Fig. 32) than from verbal 
statement. 

While the restricted areas described above are probably 
the more immediate sensory receiving stations in the cortex, 
it is not to be assumed that they are the only areas con- 
cerned. We have evidence that about both visual and 
auditory areas are regions that have a related function. 
Injuries in the temporal lobe near the primary auditory 
centre tend to decrease the efficiency of hearing. Lesions 
of the occipital lobe near the primary visual areas give rise 
to partial blindness or inability to interpret or perceive 
objects. These regions may be assumed to be active in 
connecting and elaborating the impressions received from 
the sense in question, rather than serving as the primary 
receiving centers. 

Association Areas. — As will be seen from the diagrams, 
these projection areas, taken even in the wider sense of the 
last paragraph, include relatively small portions of the total 
area of the hemispheres. It was long a question what the 
functions of the other regions might be. Flechsig may be 
said to have found the answer. By his method of tracing 
the course of developing nerve tracts, he showed that masses 
of fibres led from the projection areas to the other regions 
of the brain, — that some were connected with few, some 
with many of these regions. He inferred from this that all 
of the cortex not included in the projection areas serves in 



FUNCTIONS OF THE FRONTAL LOBES 69 

association. He even attempted to assign specific associa- 
tory functions to different areas. The posterior portions of 
the parietal and temporal lobes and parts of the occipi- 
tal lobe he called the parieto-occipital association areas, 
and he assumed them to have the function of forming con- 
nections between the neighboring sense areas, and to be 
the seat of such associatory functions as those involved in 
the perception of space. The frontal lobe, so far as it is not 
included in the motor area, he makes the seat of the more 
complicated associations involved in reason and judgment. 
While the specific functions of different regions cannot be 
said to be matters of agreement, it is safe to hold that the 
general function of the silent areas is to make possible wide 
and greatly varied associations between the projection 
areas. There are formed the innumerable connections 
between different sensory processes and between sensory 
processes and movements so important for our daily hfe. 

Functions of the Frontal Lobes. — Specific evidence of 
the dependence of associations upon the frontal lobes was 
obtained by Franz in experiments on cats and apes. When 
he taught his animals to make certain responses to given 
stimuH, and then removed part of the frontal lobes, the 
recently formed associations were destroyed, but an act 
that had been well learned was not disturbed by the opera- 
tion. Animals that had been operated upon and had 
recovered, could learn new movements, and these were again 
destroyed by a second operation. It might be argued that 
the results noted were due, not to removal of a particular 
area of the brain, but to the shock or other general effects 
of the operation. To obviate this objection Franz removed 
other parts of the brain in control animals and found that 
the operation was without effect upon retention. He 
beheves that his results have established the close connec- 



70 FUNDAMENTALS OF PSYCHOLOGY 

tion of the frontal lobes with associations. Clinical obser- 
vation in general supports the view that the frontal lobes 
are important association regions and the seat of compK- 
cated intellectual operations. When these are injured, the 
patient is usually incapable of the higher mental acts, is 
said to lose his character, to be reduced to idiocy or to a low 
mental state. On the other hand, considerable portions 
of the frontal lobe may be lost without any apparent effect 
upon the individual. Probably the two sets of facts are 
to be brought into harmony on the assumption that any 
part of the area may be used for associations; after asso- 
ciations have been formed in some one part and that part 
is removed, the knowledge is lost. When a portion is 
removed in which no connections have been made, no 
change in the animal can be noted. 

Aphasia. • — The cooperation of the various areas of the 
cerebrum in mental operations can be well illustrated by a 
study of the facts of aphasia, which we may undertake as 
a final review. This is one of the most familiar defects, 
and is also illuminating because speech stands in such close 
connection with all of the other mental operations. By 
aphasia is meant the loss of speech due to any lesion of 
the brain. Two forms of aphasia are ordinarily distin- 
guished. One, motor aphasia, is characterized by inabihty 
to produce the vocal movements in a coordinated fashion, 
and has been connected since Broca's time with a lesion in 
the third frontal convolution, an area in front of the imme- 
diate motor centres for the muscles of the head and throat. 
The other is sensory aphasia, first reported by Wernicke in 
1874. It is more closely connected with inabihty to hear, 
or to think of the word, a word deafness, and has been 
shown to be due to injury of the auditory centre and of the 
immediately contiguous areas of the temporal lobes. 



PARTIAL APHASIAS 



71 



Partial Aphasias. — In addition to the cases which show- 
complete loss of function, together with loss of capacity to 
hear or to anticipate the pronunciation of words, one must 
recognize instances in which the patient can hear mentally, 
can reproduce words to himself, but cannot hear when 
words are spoken. On the other hand, there are patients 
who can recall the 'feehng' of words as they are spoken, 




Understanding' 
of writing. 



Fig. 3S- — Diagram of speech areas. (From Bing, op. cit.) 

can have all the antecedents of speech, but cannot speak. 
In these cases lesions have been found in the subcortical 
regions which affect the projection fibres on the path to 
the muscles. All the cortical processes go on as usual, but 
the connections with sense organ and with muscles are 
broken. Other distinctions can be made in sensory aphasia, 
in particular between injury of the primary receiving centre 
and the adjoining elaborating or memory areas. Thus, ac- 
cording to Adolph Meyer, when the first temporal gyre on 
the side next the island is injured, 'word-deafness' re- 



72 FUNDAMENTALS OF PSYCHOLOGY 

suits. In case the lower portion of the gyre is injured, on 
the other hand, words are spoken hit or miss, what is 
called a 'word-salad' is frequent, memory for words seems 
disturbed but not destroyed. Still another element must 
be added to give a complete picture. Other than the audi- 
tory memories are necessary before the words can be un- 
derstood in their completeness. This has been pictured by 
Wernicke and others as a process of connecting the word 
with a concept in a concept centre. The concept centre is 
probably too simple a way of disposing of the process, but 
it is necessary to connect the word or sound with a large 
number of other experiences before it is understood. With 
suitable reservations this may be interpreted to mean that 
the auditory impression makes many associations before it 
is transferred to the motor centre. If these connections 
are impaired, repetition of sounds heard is possible, but 
there is no understanding of what is heard, and no proper 
control of what is said. 

Five operations may be thought of as necessary for 
speech: i, the reception of the sound in the primary 
centre for hearing; 2, its elaboration in the association 
region about the primary centre; 3, more complete elabo- 
ration by reference to other than auditory experiences 
(transfer to the h3rpothetical concept centre); 4, arousal 
of the coordinated motor impulses in Broca's centre; 
5, conduction of these to the separate motor centres, from 
which the impulses are sent down to the muscles. The 
functions of areas 4 and 5 are related in very much the 
same way that a higher coordinating region, such as the 
cerebellum, is related to the activity of a mere reflex cen- 
tre. In the primary motor area, a single muscle or muscle 
group is made to contract by stimulation; in the Broca 
centre, a large number of sensory stimuli are coordinated 



PARTIAL APHASIAS 



73 



and distributed to each of the different motor centres to 
cause just the right amount of contraction in each muscle 
at just the right time, — to marshal the different compo- 
nent movements to produce a satisfactory total result. The 
disappearance of any of these centres, or of the connections 



Broca's 
centre." 




Centre for 

— — muscles of 

articulation. 



Fig. 34. — Showing connections broken in cortical and subcortical motor apha- 
sia. In the former, i, 2, and 3 are interrupted; in the latter only 4. (From Bing, 
op. cit.) 



between them, produces aphasia, or in less serious cases, 
paraphasia. 

Other centres that have been connected with the speech 
processes are the reading centre, which is localized on the 
lateral occipital lobe, and the writing centre. The reading 
centre has the same relation to the primary visual centre 
as has the auditory speech centre to the primary auditory 
centre. It may be imagined to be the region in which the 



74 FUNDAMENTALS OF PSYCHOLOGY 

visual pictures of words are supplemented with memories 
and thereby understood. When the centre is injured, read- 
ing becomes impossible or inaccurate. The writing centre 
is not so generally accepted now as it was a decade ago. 
There have been a few cases of an inability to write with 
retention of abihty to speak, but it is assumed that these 
were due to injury below the cortex or to paralysis of the 
arms due to lesions in the cortical area for the control of 
arm movements, rather than to the destruction of a single 
centre for the coordination of the specific movements in- 
volved in writing, similar to Broca's centre for speech. It 
should be said, in leaving the discussion of speech func- 
tions, that the cases are by no means so clear cut as one 
might wish. There is much contradiction and confusion in 
the reports of cases made which is only partially harmonized 
in such a schematism as that given above. Still this may 
be regarded as a simple picture of what takes place. 

The Left Cerebrum Dominant. — It should be empha- 
sized that, in right-handed individuals at least, the speech 
functions have their seat in one hemisphere mainly, the 
left. In cases of injury to the right brain in what corre- 
sponds to Broca's or Wernicke's centres, speech suffers 
little injury. Apparently this is only one phase of the 
general fact that in right-handed individuals the left hemi- 
sphere cares for the more important and delicate coor- 
dinations, while, wdth exceptions, the right hemisphere 
dominates in the left-handed individuals. If an injury be 
done to the right hemisphere in the third frontal convolu- 
tion but the primary motor centres be not injured, the 
speech functions are not disturbed. Similarly, when the 
motor region in the left hemisphere is injured but the right 
is unaffected, it is found that the left hand is rendered in- 
capable of delicate movements, although there is no sign 



THE LEFT CEREBRUM DOMINANT 



75 



of paralysis and the coarser movements are unaffected. 
Liepmann found one case in which both hemispheres were 
normal, but where there was a lesion in the corpus callo- 
sum, the mass of fibres which connects one cortex with the 
other (Fig. 35). In this case, the right hand was normal, 




To left hand 



NT*. 



-^^ To right hand 



Fig. 35. — Showing the lesions that might break the connections between the 
left and right hemispheres and so produce apraxia of the left hand. If the lesion 
is at I, the right hand will be paralyzed as well; if at 2 or 3 only apraxia of the 
left hand is caused. (From Bing, op. cit.) 

the left what is called apraxic, — that is, delicate move- 
ments could not be carried through with accuracy. These 
cases indicate that the highest coordinations, whether in 
speech or in manual exercises, are accomphshed in the left 
hemisphere. It has been suggested that right-handedness 
is really left-brainedness, and vice versa. 



76 FUNDAMENTALS OF PSYCHOLOGY 

Restitution of Function. — Interesting, too, in this con- 
nection is the fact of restitution of function in cases of 
cerebral lesions. Not infrequently an aphasic will show 
marked improvement, sometimes almost complete recov- 
ery, with no betterment of the lesion. In surgical cases 
the patient will frequently show considerable paralysis im- 
mediately after part of the cortex has been removed, but 
with the passage of time his movements will become nor- 
mal again. Various speculations have been indulged in to 
explain this phenomenon, such as that the function is taken 
over by the other hemisphere, that the paralysis is due to 
shock, and when that passes, the old structures regain their 
activities, or in general that some other part of the nervous 
system can take over the work. No one of these theories 
has received general acceptance, nor can any be said to be 
altogether satisfactory, but it is important in several con- 
nections to note that there is a considerable degree of flexi- 
bility in function exhibited by many of the nervous struc- 
tures. Surgeons have joined part of the central end of a 
flexor nerve to the peripheral end of an injured extensor 
nerve and, when regeneration has taken place, the nerve 
and its central connections perform the new function with- 
out a hitch. In cases of destruction of paths through the 
cord, as in infantile paralysis, it is found that other paths 
will be substituted and the paralysis disappear in time, 
provided only that the muscle be kept from degenerating 
while new paths are being developed. Vicarious func- 
tioning, replacing of one structure by others, seems to 
be a fairly general law of nervous action, although much 
remains to be learned of the Hmits and details of the 
process. 

Resume of Nervous Functions. — In brief, then, we see 
that in the nervous system, the action of all parts depends 



THE ACTION OF THE SYNAPSE 77 

upon a transfer of sensory impulse to motor neurones, and 
the consequent excitation of muscular movements. There 
are three levels in the nervous system at which the transfer 
from sensory to motor organs may take place: i, at the 
level of the simple reflex in the cord or brain stem; 2, in 
the higher coordination centres in the brain stem, the cere- 
bellum, and the corpora quadrigemina; and 3, in the cor- 
tex. As one passes to the higher levels, the number of sen- 
sory impulses concerned in guiding movements becomes 
greater, and in consequence the movements become more 
accurately adjusted to the environment, to the circum- 
stances of the moment. In the cortex, the association cen- 
tres provide regions where all sense impressions may be 
brought into connection with each other and with retained 
impressions, and where all combine to control movements. 
Action is in the light of past as well as of present experi- 
ence. In consequence, the highest forms of adaptation are 
possible. Aside, however, from the increasing complexity 
of interaction, the highest and the lowest forms of nervous 
action follow the same laws. The control of the path taken 
by the impulses through its structures may also be ex- 
plained on the same general principles. 

The Synapse 

The Action of the Synapse. — Perhaps the best notion 
of these principles is given by a theory elaborated by Pro- 
fessor Sherrington. This regards the course of an impres- 
sion through the nervous system as determined by the ease 
or difficulty with which nerve processes may pass from one 
neurone or nerve element to another, the amount of re- 
sistance at the synapses. This has already been briefly 
mentioned in the preceding chapter. The great number of 
synapses that may be crossed can be seen in Figure 36, 



78 



FUNDAMENTALS OF PSYCHOLOGY 



which shows the large number of collaterals and end 
brushes of a single neurone from the cerebellum of a rat. 

The final explanation of why one synapse should be 
more permeable than another, and why the same synapse 
should be more easily crossed at one time than at another, 
has been the subject of much discussion and is not com- 
pletely agreed upon as yet. The earhest and simplest ex- 
planation grew out of the picture of the nervous system as 




Fig. 36. — The numerous points of connection of a neurone from the cerebellum of 
a rat. (Cajal.) 

a colony of individual cells, each hke an amoeba, which 
could control in some degree the extension and withdraw- 
ing of processes. Just as a group of amoebae that hap- 
pened to be in contact might send out pseudopods and 
touch each other at different times and places, so the neu- 
rones might on occasion send out or increase the length of 
the dendrites until they came into contact with the end 
brushes of the neighboring axones. It was further assumed 
that when physical contact was present between the neu- 
rones, a nervous impulse might pass, while at other times 
the path was blocked. Some authorities asserted that the 



THE ACTION OF THE SYNAPSE 79 

dendrites were shorter in animals killed by an anaesthetic 
than in others. The theory was used to explain sleep as 
due to a blocking of all the pathways to consciousness. 
Later consideration has led to the abandonment of the 
theory. It would make all action of the nervous system 
depend upon chance activities or arbitrary activities in the 
separate cells, rather than upon the way they were affected 
from without, or by other cells. Sleep might be satisfac- 
torily explained, but on this theory it would never be pos- 
sible to waken the individual until his neurones were ready 
to put out their dendrites again. 

Sherrington is convinced from a careful study of the 
times required for the reflex movements under different 
conditions, that we must think of the nervous structure as 
continuous. A membrane at the synapse, probably analo- 
gous to the membrane of a cell, offers a resistance to the 
passage of the impulse. The degree of resistance is de- 
termined by the degree of permeability of the membrane. 
The neurones would always be in contact, the reflex path 
is always continuous, but the impulse is impeded at the 
point of contact between axone and dendrite. 

If we may be satisfied with the theory, we still have to 
ask why one synapse should be more permeable than an- 
other. In the lower centres it may be assumed that the 
openness of certain synapses and the closed condition of 
others is inherited, that it either is present at birth or ap- 
pears soon after as a result of the inherited predisposition. 
Few reflexes are perfect at first, — they improve for days 
or even weeks in the higher animals. At first the child 
does not accurately touch a point stimulated, although 
there is usually some indefinite waving of the arms. Many 
of the more compKcated reflexes and instincts make their 
appearance late, although probably the development comes 



8o FUNDAMENTALS OF PSYCHOLOGY 

in large part as a result of growth rather than of learning. 
The paths open at birth determine a relatively larger pro- 
portion of the total number of paths in the cord and mid- 
brain than in the cortex, but probably form a large number 
of the total connections even in the adult cortex. The gen- 
eral Unes of connection are pretty well laid down even there. 

Habit a Change in the Synapse. — The connections that 
develop in the hfe of the individual as a result of learning 
are due to changes that take place in the character of the 
synapse. What this change is is not determined and can- 
not be, so long as we do not know what the nature of the 
opposition in the membrane may be. We do know that 
the more often two neurones are excited together or in 
immediate succession, the greater is the hkeHhood that the 
activity of one will extend to the other. All learning, 
whether in the formation of habits or in the connection of 
sensory impressions in sensory learning, is due to this re- 
duced resistance. The laws that govern the reduction of 
resistance from use are known in some degree from the ob- 
servations of the behavior of the organism, but our theory 
takes us only to the point where we may say that learning 
is due to some sort of reduction in the resistance offered by 
the synapse to the passage of the nervous impulse. 

Our picture of the action of the cortex, as of the cord, is 
that all is determined by the openness of paths, by the 
synapses. The passage of the impulse from sense organ to 
muscle is, as has been emphasized repeatedly, the expla- 
nation of all function, whether in cord or in cerebrum. The 
difference between the two is that there are more open 
paths in the latter over which any impulse may pass and 
that for the most part these paths have been opened by 
use, by the earher activities of the organism. It should 
also be emphasized that many different stimuH cooperate 



FACILITATION OF IMPULSES 8i 

in producing the activities that result from the action of 
the cortex, many more than act together in any of the 
lower centres or organs. The cooperation is made possi- 
ble by the fact that many of the paths have common 
parts; in fact, that the motor part of the path is common 
to very many different acts. In the majority of cases the 
same muscles, and even the same groups of muscles, are 
used. The excitation of the motor path may be aroused 
by a number of sensory impressions, and the various im- 
pressions may be thought of as cooperating in the final 
action. What is even more important in this connection is 
that each sensory impression may be connected with sev- 
eral motor or intermediate neurones, and the action which 
results when the sensory impression is received must de- 
pend upon the openness of the various synapses, of paths 
leading to the possible motor organs that may be excited. 
Where very large numbers of stimuli are presenting them- 
selves at every moment, there must be a large amount of 
coordination, of reciprocal influence, to determine which 
of the possible movements is actually made. The strong- 
est impression and the one whose neurone has the most 
open synapses between it and the motor neurones will de- 
termine the action. 

Interactions of Impulses 

Facilitation of Impulses. — In addition to this mere 
openness of paths and the greater strength of the impres- 
sions, coordination seems to imply mutual interaction be- 
tween the neurones of one path and those of another. 
Sherrington and others have demonstrated two forms in 
which one path or series of neurones may act upon others. 
One, the more direct, is some process of making easier the 
path for one response by another set of neurones active at 



82 FUNDAMENTALS OF PSYCHOLOGY 

the same time. This is very common. It may be illus- 
trated very easily by the knee-jerk. You are familiar with 
the fact that if you strike sharply the tendon below the 
knee-cap when one leg is crossed over the other, the foot 
will give a kick. It has been shown that the kick will be 
much stronger if the hands are clenched at the time the 
blow is given. The clenching of itself would not produce 
the kick, but it prepares the way for, or facilitates, the re- 
sponse when the blow is given. This may be pictured as a 
preparatory reduction of the resistance of the synapse 
which makes the impulse pass more easily, and hence with 
greater intensity, when the suitable stimulus is appHed. 

Inhibition of Impulses. — More striking is the second 
form of interaction, inhibition. Certain paths when active 
prevent the action of others, or reduce their liability to re- 
sponse. Sherrington has demonstrated this phenomenon 
in the case of many reflexes, such, for example, as the gen- 
eral reduction of the strength of the reflexes of the cord 
when it is in connection with the cerebrum. After the cere- 
brum has been removed and the animal has recovered from 
the shock of the operation, all reflexes are exaggerated, a 
fact explained on the assumption that in the normal animal 
all lower reflexes are inhibited by the higher centres. More 
interesting for our immediate purpose is the fact, fully es- 
tablished by Sherrington and Hering, that the flexor and 
extensor centres in the cortex mutually inhibit each other. 
They removed the flexor muscles of a member, placed the 
animal in such a position that there was a tendency for 
flexion, — it was supported only by the extensor muscles, 
— and noted that the member was lowered when the flexor 
centre was stimulated. This they explained as an inhibi- 
tion of the cortical centre of the extensor muscle from the 
flexor centre which reduced the tonus of the extensor, and 



CONSCIOUSNESS AND CORTICAL ACTION 83 

so permitted the member to be flexed. This was also dem- 
onstrated on the antagonistic eye-muscles. If the internal 
muscle of the eye were severed and the cortical centre for 
that muscle were stimulated, the eye would turn as it does 
upon stimulation of that centre when the muscle is intact. 
This mutual checking of antagonistic movements prevents 
any possibility of interference between groups of muscles 
in voluntary action. It makes it impossible that one group 
of muscles should pull against another. Inhibition is -as- 
sumed by Sherrington to be due to the action of one set of 
neurones upon a synapse somewhere along the other path 
of discharge. The activity of that set of neurones, in some 
way as yet unknown, makes the membrane at the synapse 
much less permeable, and so prevents "the discharge of the 
impulse across it. 

These processes of facilitation and inhibition are -quite as 
essential to the interaction of various stimuli in the cortex 
as in the lower centres. As will be seen from time to time 
in considering the mental processes, the most important 
and striking fact is the wide interaction of mental pro- 
cesses. It is seldom that an act 'or a thought is 'controlled 
by a single stimulus alone or even by the stimuli that are 
being received at the moment of action. The laws of .fa- 
cilitation and inhibition of one set of cortical activities by 
others that are going on simultaneously in other paths and 
in other areas, are needed if we are to obtain any accurate 
picture of cortical action. We shall have occasion to recur 
to these interactions in our explanations of mental processes. 

Consciousness 

Consciousness and Cortical Action. — The relation of 
consciousness to the total action of the brain may be 
briefly mentioned. On the physical side, the action of the 



84 FUNDAMENTALS OF PSYCHOLOGY 

nervous system may be thought of as the passage of chem- 
ical or electrical changes or processes -through its various 
structures. These are present not at a single place but 
everywhere throughout the mass of neurones, — hundreds, 
if not thousands, of separate sensori-motor arcs are carry- 
ing impulses at the same time, — for the muscles not only 
are moved by nerve impulses when they move, but are also 
kept in slight or tonic contraction by the constant action 
of the neurones. But of all these activities, only relatively 
few, perhaps not more than one group at a time, are ac- 
companied by clear consciousness. The others do their 
work without being noticed. If they contribute at all to 
consciousness, it is only by modifying the total mass in 
some slight degree. They are silent servants, or their 
addition is lost in the complex. The general rule is that 
consciousness attaches to activities which are performed 
for the first time, or which offer special difficulties. As 
movements are repeated, they gradually cease to attract 
attention, and usually by the time they can be carried out 
effectively, only the intention or the first beginnings of the 
act are conscious. There is *no evidence, however, that 
the impulse follows any distinctively new path after it 
ceases to be conscious, that a voluntary act is first carried 
out by the cortex, for example, and then by the lower cen- 
tres. It seems probable rather that consciousness drops 
away as the impulse crosses the synapses more easily. 
The paths followed are still the same when the action be- 
comes easy, but we are not aware of the activity. 

The Autonomic System 

The Autonomic Nervous System. « — In -addition to the 
central or cerebro-spinal nervous system which w-e have 
outlined above, the psychologist must also mention the 



THE DUCTLESS GLANDS 85 

so-called autonomic nervous system. The autonomic sys- 
tem as a whole consists of a number of ganglia, whose 
function is to receive motor impulses from the cord and 
brain stem and distribute them to the viscera and glands 
that they excite. As compared with the central nervous 
system, the responses are very slow and are diffused 
throughout several organs, rather than being restricted to 
isolated groups of muscles. These ganglia lie on both 
sides of the spinal column in the central trunk and in the 
head and pelvic region are found near the organs they 
excite. They all receive fibres from the cranial nerves and 
spine. Fibres from the central nervous system make con- 
nections with the cell bodies of the autonomic system, and 
from these cell bodies non-medullated fibres extend to the 
organs which they innervate. They are distributors of 
motor impulses from the central nervous system. 

Impulses from the autonomic system extend to all parts 
of the body. They cause contraction of the blood vessels, 
erection of the hairs in animals, changes in the size of the 
pupil, secretions of the glands, including the sweat glands, 
increased rate of the heart, movements of the walls of the 
intestines, the movements of excretion, etc. They are pre- 
eminent in the control of the fundamental bodily mechan- 
isms. They affect consciousness most through their activ- 
ity in emotions. 

The Ductless Glands and the Activity of the 
Nervous System 

The Ductless Glands. — A series of organs and activi- 
ties which need to be taken into account in connection 
with the activity of the nervous system and which depend 
upon the action of the autonomic system has been discov- 
ered relatively recently, the endocrine or ductless glands. 



86 FUNDAMENTALS OF PSYCHOLOGY 

These glands secrete certain substances, known as hor- 
mones, directly into the blood. These hormones are essen- 
tial to the proper functioning of the nervous system in par- 
ticular and to the growth of many other parts. The hst of 
glands which influence the nervous functions includes the 
thyroid and pituitary, the adrenal glands and certain parts 
of the sex glands. Possibly we should include also the 
thymus and pineal glands, although relatively Httle is 
known of their functions. 

The Thyroid Glands. — The best known are the thyroid 
glands, relatively large masses in the front part of the 
throat (which, when abnormally enlarged, produce goi- 
tres). The secretions of the thyroid are essential to the 
mental life and to the proper growth of brain. A cretin, 
who is an individual with defective thyroid secretion, is of 
the mental level of a child of four or five, is short in stat- 
ure, with general infantile contours of the body. That this 
is due altogether to lack of thyroid secretion is shown by 
the fact that feeding a developing child thyroid extract 
from a sheep induces a marked growth and increase in in- 
telligence. A marked cretin at two years may be a nor- 
mal child at three. The treatment must be begun early if 
it is to be effective, and the improvement will continue 
only so long as the treatment is kept up. Excess of thy- 
roid secretion, on the other hand, induces an abnormal ex- 
citabiHty, particularly of the emotions. Hyperthyroidism 
is marked by excessive pulse rate, by wasting, and muscu- 
lar weakness, and by great irritability. 

The Pituitary Body. — The pituitary body is a small 
protuberance on the under surface of the brain stem, just 
back of the optic chiasma, or crossing of the optic nerve. 
It is connected with the third ventricle by a hollow tube. 
Three parts can be distinguished, with secretions differing 



THE DUCTLESS GLANDS 87 

in function. The anterior portion secretes a substance 
that promotes the growth of the body, particularly of the 
bones and connective tissues. Cases of giantism, asso- 
ciated with mental disturbances, have been traced to ex- 
cessive secretions of this anterior lobe. The intermediate 
portion secretes a substance which increases the contrac- 
tion of unstriped muscles, and another substance which 
probably passes directly into the ventricles of the brain 
and is essential to the proper functioning of the cortical 
tissues. Disturbances of this secretion result in a marked 
decrease in intelligence. The function of the posterior por- 
tion is not known. 

The Adrenal Glands. — The adrenal glands are small 
glands near the kidneys, which have connections with the 
sympathetic nervous system. Excitation of the fibres in- 
nervating these glands induces a secretion directly into the 
blood that increases the heart rate, changes the composi- 
tion of the blood, and causes the flow of glycogen from the 
liver. This adrenal secretion is an important factor in 
emotional excitement and we may postpone details until 
we consider them in that connection. 

Other Glands. — It has been suggested that the pineal 
gland may have a similar function, possibly to inhibit the 
effects of the pituitary secretion, but the evidence is con- 
tradictory, and we must await further evidence before we 
can include it among the endocrine glands. The same may 
be said of the thymus. 

The ductless glands as a whole are important because 
they secrete substances which are essential to the growth 
of the nervous system and to its proper functioning. For 
psychology, they have an interest since their action is in- 
volved in the action of the nervous system, and more par- 
ticularly since in emotional reactions they influence the 



88 FUNDAMENTALS OF PSYCHOLOGY 

responses of the vital organs directly, and indirectly they 
render the individual more susceptible to emotional reac- 
tions. 

Body and Mind 

The Relation of Body and Mind. — Much of modern 
psychology since Descartes has dealt with the relation of 
the mental processes to the nervous processes which we 
have just been discussing. The problem originated from 
the fact that behavior may be studied in two ways, from 
without and from within. When one attempts to study 
man with the scalpel and the instruments of the physiolo- 
gist, he deals always with the physical man, with nerve 
and nerve cell, with white matter and gray matter, but he 
never finds any trace of sensation, of the inner experience. 
On the other hand, when one studies the mental states 
and devotes oneself to what can be seen in one's own con- 
sciousness, alone, one never finds any immediate evidence 
of nerve cells. For the most part investigators have pre- 
ferred one or the other of these approaches to the facts of 
mind, — few men have given due credit to both. Even 
where each attracts the interest of the same man, it is sel- 
dom that both are combined in a single statement, or com- 
pletely harmonized. More frequently one is entirely sub- 
ordinated and to all intents and purposes we are given an 
explanation that is either completely materiahstic or alto- 
gether spirituahstic. . Most writers compromise, and in 
subordinating one of the two series they make it almost 
incidental, without real force, a sort of ghost of mind or of 
body, as the case may be, which merely follows the activ- 
ity of the other but has no influence upon it. 

Very generally, at present, the two Hnes of approach are 
recognized and both of the resulting series of experiences 



THE RELATION OF BODY AND MIND 89 

are accepted as real. The most troublesome problem is 
that of the relation between them. Two theories as to 
this relation may be recognized. One takes the natural 
attitude that the two series interact, as do series of phys- 
ical events; that when a sense impression is received, it is 
transmitted to the brain by the paths we have indicated, 
and that in the brain it in some way gives rise to the in- 
corporeal process we know as sensation or knowledge, in 
the same way that the vibration of a sounding body may 
give rise to vibrations in the air. Similarly, it is assumed 
on the other side that voluntary processes may produce 
changes in the nervous system and so in the physical uni- 
verse, just as simply as do physical forces in other physical 
objects. This theory of the relation of body and mind is 
known as inter actionism. 

Another theory equally current at present is known as 
psychophysical parallelism. It is an expression of the con- 
servatism of modern thinkers in refusing to assert any par- 
ticular sort of relation between body and mind. The men- 
tal series is assumed to constitute one train of events which 
can be explained in terms of earlier mental events; the 
physical series, the changes in nervous elements, is made 
entirely distinct, and it is assumed that it can be completely 
explained in terms of the antecedent physiological pro- 
cesses. The relation between the two series either is left 
unexplained or it is said positively that there is no in- 
teraction between them. In recalHng an event, for exam- 
ple, one would run through a series of ideas until the 
proper associate presented itself. On the physical side, 
the series in recall would depend upon the connections that 
had been established between neurones in different sensory 
areas of the cortex, and the action resulting from the recall 
would be due to the transfer of some nervous excitation 



90 FUNDAMENTALS OF PSYCHOLOGY 

from a sensory area to the corresponding motor area. 
When it is asked, however, how it happens that the nerv- 
ous processes are always accompanied by the mental states, 
one of two answers is made. The more extreme men as- 
sert that there is no present connection between the two 
series of events. Each runs its own course because of 
some of the antecedent events within itself, but nothing 
that happens in the other can influence it. The two are 
kept together because they go at the same rate, rather 
than because of any cross connection between them. Mem- 
bers of the other school are less dogmatic in the negative. 
They assert merely that they do not know the nature of 
the connection, not that there is no connection between 
the two series. 

The evidence adduced by the upholders of each theory 
is largely negative. The negative considerations upon 
which paralleHsm is based are the fact that one never can 
appreciate both series at the same time, can see nothing 
pass, and that the two series of events are not at all com- 
parable. One cannot think of a thought moving a stone, 
or, in CHfford's term, it seems absurd to assert that two 
cars are coupled by the bond of affection between guide 
and guard, and to speak of a thought making any change 
in nerve cells is on exactly that level. At times the argu- 
ment is given a more formal turn in the assertion that to 
assume interaction is in violation of the doctrine of the 
conservation of energy. If the physical series is to be re- 
garded as a closed system of energy, it can neither give off > 
energy to the mental states as is required if sensations are 
to be caused, nor can it be changed by mental states, as 
would be necessary if human voHtions were to exert an in- 
fluence upon the nerve cells. In passing upon these objec- 
tions, one must remember, however, that the doctrine of 



THE RELATION OF BODY AND MIND 91 

conservation is itself only a principle that has been set up 
for convenience, and must be given up if it should cease to 
harmonize with facts, and also that it may be possible in 
the future to include the mental world in some wider sys- 
tem of relations in which the mental and the physical shall 
be brought together. The objection is more formal than 
real. We come back, then, to the original assertion that 
we cannot make a single observation that will include a 
mental event and the physical event which causes it or is 
caused by it, and in consequence cannot obtain even an 
approximate picture of how one is related to the other. 
There is not so much as a good analogy for the connection, 
and most explanations are analogies. 

On the other hand, the interactionist insists with great 
firmness that mere failure to see what happens when two 
events succeed each other uniformly, does not prove that 
they do not stand in some active relation, even in causal 
relation to each other. It is very seldom, if ever, that one 
is actually aware that some force has passed from one phys- 
ical object to another; one seldom knows anything of what 
has taken place between them. The ability to trace energy 
relations is the exception rather than the rule. In other 
words, the relation between the mental and the physical 
series of events is no more unknown than is any other ac- 
tive relation. There is therefore no more objection to re- 
garding the psychophysical relation as causal than the 
relation between heating and expansion or any other sim- 
ple physical relation. Physical cause is itself not under- 
stood, and, if one goes deep enough, is as much a mystery 
as the relation of mind and body. While one may grant 
all this very readily, it does not necessarily follow that to 
change from one side to the other too often and too quickly 
— to introduce mental elements into the physical series 



92 FUNDAMENTALS OF PSYCHOLOGY 

and physical into the mental series — may not give rise to 
vagueness and uncertainty. As a matter of fact, while one 
may admit that there are causal interconnections between 
nervous system and mind, it is also true that many argu- 
ments become vague if the speaker jumps from one series 
to the other for an explanation. While we shall admit that 
mind and body undoubtedly interact, we shall endeavor as 
far as possible to keep the explanation of physical states in 
terms of antecedent physical states, and the explanation 
of mental states in terms of antecedent mental states, and 
assume as little interaction between the series as is possible. 
It is necessary to accept an effect of the sense organs and 
sensory neurones upon consciousness to understand the 
material of consciousness and an influence of voluntary 
processes on muscles if we are to understand action. Aside 
from these, however, clearness demands that all mixing of 
the two sets of explanations be avoided. 

REFERENCES 

Bing: Compendium of Regional Diagnosis. 

Dunlap: Outline of Psychobiology. 

Herrick: Introduction to Neurology. 

Ladd-Woodworth : Physiological Psychology. Pp. 13-293. 

Strong: Why the Mind has a Body. 

MacDougall: Body and Mind. 

Starling: Physiology, Ch. VII, §§ xvii-xix. ' 

Schaeffer: The Endocrine Glands. 

VON MoNAKOW: Die Lokalisation im Grosshirn. 



CHAPTER IV 
SENSATION 

General Remarks 

We have seen from our discussion of the action of the 
nervous system that all nervous action starts in sensation 
and leads to movement. The first half of this assertion is 
to be our guiding principle in discussing the qualities of 
consciousness. All the materials of our knowledge are 
derived from sensation. We have just as many different 
sorts of consciousness as we have quahties of sensation, and 
consciousness persists apparently only so long as impres- 
sions are playing upon our sense organs. The old sensa- 
tionalists, Hobbes and Locke, for example, insisted that 
there could be nothing in mind that had not previously been 
in sense. While we do not to-day accept the principle quite 
so Hterally as they did, yet it is easy to see that the funda- 
mental qualities of mind are derived altogether from the 
external senses. One can imagine no color or sound that 
has not at some time been seen or heard; or, to put it more 
conservatively, one can call to mind no quaHty of any kind 
that has not at one time come through the senses. One 
caimot picture the color of an ultra-violet Hght, or think 
what it would be like if one were suddenly to develop a 
sense organ that might be affected by it, nor can one think 
how the magnet might affect one if some sense organ should 
be developed to respond to it. Memory, imagination, and 
reasoning are Hmited in the quahties that they make use 
of to the bare materials of sense. They may recombine 

9i 



94 FUNDAMENTALS OF PSYCHOLOGY 

them, they may make use of the sense materials in new 
ways, but they can add no new quaHties. 

Classification of Sensations. — The qualities of sensa- 
tion might conceivably depend either upon the nature of 
the stimulus or upon the nature of the receiving organ. The 
popular mind accepts the former, but most psychologists 
beheve that they are determined by the character of the 
sense organ or the connected portions of the nervous system, 
by the nature of the sensory ends that are turned outward 
to the physical world. That the nature of the sensation 
does not depend altogether upon the stimulus is evident 
from the fact that different stimuK produce the same sensa- 
tion when they affect the same sort of nerves. Thus we 
shall see that menthol, pressure, and heat or its lack all 
produce the sensation of cold when they act upon a cold 
spot on the skin. On the other hand, the same stimulus, 
an electric current, for example, produces a different sensa- 
tion as it acts upon different kinds of sense organs : cold on 
a cold spot, Hght on the retina, etc. These facts and others 
seem to show fairly conclusively that the nature of the 
sensation is determined by the receiving organ, rather than 
by the stimulus that is applied; by the character of the 
receiving tissue that has been developed, rather than by 
the character of the outside world. If this be accepted 
provisionally, it furnishes a convenient means of classif5dng 
sensations. Could one but determine the different sorts of 
sense ends that come to the surface of the body or are im- 
bedded in its substance, one would also have a complete 
hst of the possible sensations. In practice one usually dis- 
criminates the sense quality first and later discovers the 
sense organ, but the classification nevertheless is assumed 
to be in terms of the sense organ. We may accept for the 
moment the general principle that the number of sense 



ATTRIBUTES OF SENSATION 95 

qualities is determined by the number of sorts of sensory- 
tissue that can be stimulated. 

The classification of sensations still offers some difficulties, 
since the fundamental kinds of sense ends must be grouped 
in some way for convenience of treatment. In certain cases 
the similar nerves are combined in some one organ. Thus 
in the eye are thousands of nerve ends stimulated by the 
same physical forces, and giving rise to similar sensations. 
In the skin, on the other hand, four kinds of sense ends are 
scattered indifferently over the surface, and while we com- 
monly speak of the skin as the sense organ of touch, there 
are really at least four different kinds of sensation received 
from the skin. Taste and smell offer an inconsistency of the 
opposite sort. The organs are distinct, but the stimuli 
are closely similar and the quaUties of sensation are not 
discriminated by the popular mind, yet science and common 
sense follow the organ rather than the quality in making 
them distinct sense departments. One may say, then, that 
in classifying sense quahties, the organ provides the first 
means of grouping, and within the organ the subdivisions 
may be either in terms of the classes of stimuli, or of the 
quahties of sensation, or of both. 

Attributes of Sensation. — When one attempts to enu- 
merate all possible sorts of mental quahties or sensations, 
one sees very quickly that there are various kinds of differ- 
ences that are not on exactly the same level. It is not 
possible to arrange all the different kinds of sensation from 
any organ in a single series, the members of which differ 
from each other in one respect only. Thus in the case of 
sound, we may distinguish differences of pitch and also 
differences of loudness. These vary independently. A high 
tone may be either loud or faint. These different ways in 
which sensations may vary are called the attributes of sen- 



96 FUNDAMENTALS OF PSYCHOLOGY 

sation. How many attributes there are is by no means a 
matter of agreement. All agree that one must distinguish 
differences in quality from the differences in intensity. The 
quality may be said roughly to depend upon the specific 
character of the sense organ stimulated, while the intensity 
depends upon the degree to which the organ is stimulated. 
There are exceptions to both of these statements. In the 
case of light, for example, the strength of stimulus in part 
determines the organ stimulated. It has been proved that 
faint lights are seen by one set of organs, bright lights by 
another. In the eye, too, even with bright lights, variation in 
physical intensity is not distinguished from change in quality 
of excitation. The grays correspond to changes in strength 
of Ught, but the untrained observer puts them on the same 
level with change in color. Black, white, and gray are popu- 
larly regarded as colors. But in all other senses, the distinc- 
tion in quahty and intensity offers little difficulty, and these 
two attributes are recognized by practically all psychologists. 
Extent and Duration. — More difficult it is, however, 
to dispose of some of the other attributes sometimes ascribed 
to sensations. Thus every object possesses extent, and 
every event occupies time, has duration. Many authorities 
speak of extent and duration as attributes of sensation, as 
fundamental ways in which sensations may vary. In the 
simplest cases, these ways of varying seem immediate and 
unanalyzable, but in many more instances it is possible to 
show that the appreciation both of extent and of duration 
depends upon more complicated mental operations. They 
belong rather to the object than to the sensation as such. In 
consequence it is more convenient to treat them both under 
the head of perception, as a process of mental elaboration 
of sensations, rather than as an immediate characteristic 
of the elementary sensation. Very much the same state- 



THE STIMULI FOR VISION 97 

ment may be made of clearness and feeling tone, regarded 
by some authorities as attributes. It is at least a question 
whether feehng is not entirely independent of sensation and 
an equally primary mental state. Clearness is a change 
induced in sensations as a result of their connections in 
consciousness, not an attribute of sensations themselves. 
Whether we are to regard them as irreducible parts of sensa- 
tions, or as independent elements, or as accidents of the 
ways of receiving the sensation, can be best discussed in a 
later chapter. For the present we may content ourselves 
with the statement that sensations vary in specific quality 
which depends primarily upon the nature of the receiving 
end organ, secondarily upon the character of the stimulus; 
and in intensity, which, in its turn, is dependent upon the 
amount of stimulation that affects the sense organ. Con- 
sidering quahties alone, the sensations fall into certain 
series, marked by continuous change in some one respect. 
It is impossible, however, to find similar continuous changes 
from series to series. Thus colors vary in a continuous 
series of hues; sounds show a continuous series of pitches; 
but there is no gradation from sound to sight. Through 
each quahty runs a series of intensities which is regularly 
graduated from zero to a maximum. We shall discuss first 
the quahties in their dependence upon the organ and the 
stimulus, then the intensities. 

Vision 

The Stimuli for Vision. — We may begin mth the most 
important, if one of the most compUcated, of the senses, — 
vision. The physical stimuh for sight are vibrations in the 
ether ranging from some 400 to 800 /JL/jMn length. Helmholtz 

1 nn means thousandths of a thousandth of a millimetre. This is usually 
expressed as X. 



98 FUNDAMENTALS OF PSYCHOLOGY 

under favorable circumstances saw rays as long as 835 X 
and as short as 318 X. For the average eye under normal 
conditions the values range from 760 X to 397 X. Between 
these limits Hes the visible spectrum from red to violet. 
We give names to different quahties, but it is somewhat 
difficult to say just where one color changes into another. 
The physical relations have Kttle significance for the quaHty 
of the sensation, since the colors do not change in the same 
degree as the wave length and very few of the laws of color 
can be stated in terms of the wave lengths of Kght. We 
must turn from the physical to the physiological for an 
explanation of the phenomena that interest us. For this 
we must consider the essential features of the structure of 
the eye. 

The Structure of the Eye 

The Eye and its Appendages. — The eye is a part of the 
brain that has come to the surface of the body in the course 
of its development, has increased the primary sensitiveness 
of nerve tissue to Hght by the development of new photo- 
chemical substances, and has gained a system of lenses, 
grown protective coats, and acquired a mounting that per- 
mits of ready turning in all directions. The eyes are 
mounted in deep conical sockets in the skull, where they are 
well protected. The eyeball is kept in its place in the socket 
by the capsule of Tenon, a pouch-shaped membrane that 
surrounds the posterior three fourths of the eye-ball. It 
contains synovial fluid which acts as a lubricant when the 
eye-ball turns. The muscles in its tissue also contract with 
the ocular muscles and prevent them from drawing the eye 
back into the socket. To prevent foreign particles from 
entering the socket, the front is closed by the conjunctiva, 
a membrane continuous with the inner lining of the eyehds 



THE STRUCTURE OF THE EYE 



99 



and the outer surface of the eyeball. The padding of fat, 
the conjunctiva, and the capsule of Tenon, hold the centre 
of the eye fairly well fixed, and at the same time permit 
it to turn easily about its centre. 

The Three Coats of the Eye. — The eyeball is approxi- 
mately a sphere, a little less than an inch in diameter (23-24 
mm.). The spherical shape is given it by the outer or scle- 
rotic coat, which is kept distended by the fluids within, 
submitted to constant pressure by the general circulation. 
This pressure amounts to about 25 mm. of mercury in the 
normal individual. The eyeball has three principal coats. 
The sclerotic is a tough protective coat of connective tissue. 
Inside the sclerotic is the choroid coat, made up mostly of 
blood vessels with some muscles and nerve fibres. Still 
farther within is the retina, the nervous structure and true 
sense organ. 

Each of these coats shows modifications in some part. 
The sclerotic coat in the front of the eye has a shorter radius 
of curvature, is transparent, and bulges forward as a part 
of the lens system. Here it is called the cornea. It can be 
seen to protrude from the sclerotic if one will look across 
the eye of another. Back of the cornea is a chamber 
filled with a watery fluid. This is the anterior chamber, 
and the fluid, the aqueous humor. In this chamber is an 
extension of the choroid coat, the iris, which is not attached 
to the sclerotic or cornea, but extends across the anterior 
chamber in the aqueous humor. In its centre is a hole, the 
pupil. The iris gives the color that is regarded popularly 
as characteristic of the eye. In the dark types, black or 
brown, it is much pigmented; blue and gray eyes are less 
pigmented. The size of the pupil is determined by the rela- 
tive degree of contraction of two muscles or sets of muscles : 
(i) a muscle with radial fibres, the dilator of the pupil, and 



loo FUNDAMENTALS OF PSYCHOLOGY 

(2) the sphincter, a muscle with circular fibres. These are 
controlled reflexively by the degree of stimulation of the 
optic nerve. The course of the reflex in constriction was 



Pr. cil. 
Conj. 




^—Ret 
Chor. 
Scler. 



Fig. 37. — Section of the eye; Scler., sclerotic coat; Chor., choroid; Ret., retina; 
Opt., optic nerve; Fov. c, fovea; Pr. cil., the cihary muscle or ciliary process; Conj., 
conjunctiva; Cam. ant., the anterior chamber; corpus vitreum, the vitreous humor 
that fills the main body of the eye. (From Angell's "Psychology.") 

traced on page 56. Dilation involves a reflex through a long 
path down to the cord and back through the cervical sym- 
pathetic nerve and superior sympathetic ganglion to the 



THE MECHANISM OF ACCOMMODATION loi 

eye. The widespread course of the pupillary reflex makes 
it very important in the diagnosis of nervous diseases in 
general. It is affected by lesions in many different struc- 
tures. In the normal individual, the constriction takes 
place promptly on increase of illumination, while dilation is 
relatively slow because of the long course through the sym- 
pathetic nerves. The function is in part protective by 
reducing strong Hghts, but also has somewhat the effect of 




FAR 



NEAR 



Fig. 38. — Change in lens and ciliary muscle in accommodation. Left shows accom- 
modation for distant, right, for near objects. (From Foster's "Physiology.") 

the diaphragm of a camera. It gives better definition be- 
cause it ''stops down" the pupil when the light is strong 
enough to permit and, when the light is faint, it admits more. 
Constriction of the pupil also accompanies accommodation 
to near objects. 

The Mechanism of Accommodation. — Back of the iris 
and directly against it is the lens, the most important of the 
optical mechanisms. It consists of a large number of layers. 
The front surface of the lens has in youth a natural radius 
of curvature of 4.8 mm.; the posterior surface, of 4.6 mm. 
Ordinarily, however, it is held flattened by the strain of 
the suspensory ligament. This extends from the ciHary 



\ 



I02 FUNDAMENTALS OF PSYCHOLOGY 

processes on the ciliary muscle to the edge and the front and 
back surfaces of the lens. The lens with its attachments 
constitute the mechanism of accommodation. It makes 
possible the focussing upon objects at different distances. 
The active agent is the cihary muscle. It is attached to 
the sclerotic coat near the angle formed by the increasing 
curvature of the cornea, and the fibres run back to lose 
themselves in the structure of the choroid coat. The sus- 
pensory Hgament is attached to the side of the muscle 
instead of the end, as are the tendons of other muscles, 
so that the contraction of the muscle means relaxation 
of tension on the suspensory ligament rather than in- 
crease of tension. When the tension of the suspensory 
ligament is released, the lens resumes its normal shape, 
owing to its elasticity. As one grows older, the lens 
becomes less and less elastic, and accommodation practi- 
cally disappears between 45 and 55 years. Back of the 
lens is the large main chamber of the eye, filled with the 
vitreous humor, so called because it has the consistency of 
molten glass. This fills the cavity between the retina and 
the lens. 

Dioptrics of the Eye. — Regarded as an optical system, 
the function of the eye is to project an image of an object 
upon the retina. The important refracting surfaces are 
three, the front surface of the cornea and the front and back 
surfaces of the lens. The indices of refraction of the cornea, 
and of the aqueous and vitreous humors, are approximately 
identical, and each is approximately the same as that of 
water, — i-337- The refractive index of the lens in practi- 
cal effect is 1.437. The average radius of curvature of the 
cornea is 8 mm., of the front surface of the lens is 10 mm., 
and of the back surface is 6 mm. Calculation of the 
optical efficiency of the eye from these figures gives it a 



DIOPTRICS OF THE EYE 103 

value of from 60 to 66 diopters. ^ An eye with a length of 
axis of 22 mm. must have a strength of 66 diopters if the 
rays are to be focussed upon the retina. It is assumed 
that the normal eye has a strength of 64.50 D. The nodal 
point, the point through which all light rays may be 
assumed to pass, is 15.5 mm. from the retina and about 
7.3 back of the cornea. One can think of the action of 
the lens most readily after the analogy of a pin-hole 
camera. Rays of Hght pass through a pin hole in a 



Fig. 3g. — The formation of the retinal image. Shows refraction of three rays 
of light from X and V that focusses them on the retina, and the inversion of the 
object. P is refracting surface of reduced eye. (From Foster's "Physiology.") 

screen in a straight line from the object to the image. In 
the lens the rays also act as if they passed through a single 
point, the nodal point. In the average eye, the nodal point 
is 15.5 mm. in front of the retina and 7.3 mm. back of the 
cornea. The size of the retinal image cast by objects in 
the outside world and other relations of hght rays are suffi- 
ciently accurately determined for most purposes if one 
assumes this position for the nodal point, and that the prin- 
cipal rays pass through it on the way to the retina. 

^ A diopter is defined as the strength of a lens that will bring parallel 
rays to a focus at a distance of one metre. The number of diopters of a 
lens is determined by dividing one metre by the length of its principal 
focus. A lens that brings parallel rays to a focus at 20 mm. has a strength 
of 50 diopters. 



I04 FUNDAMENTALS OF PSYCHOLOGY 

The Structure of the Retina. — The retina is practically 
a part of the central nervous system. It is a very thin coat 
of nerve tissue from .3 to .35 mm. in thickness. If we accept 
the neurone theory, the retina is composed of three layers 
of neurones, one with the modified sensory epithehum, the 
rods and cones, which receive the stimulation; one inter- 
mediate layer, the bipolar cells; and one whose cell 
bodies are the large ganglion cells nearest the vitreous 
humor. 

The rods and cones, the structures sensitive to light, are 
directly in front of the layer of pigment cells and the choroid 
coat in the outermost part of the retina. The cones are 
relatively short and thick, from 4-6 ijl {/x — .001 mm.) in 
diameter and 30-40 jj. long. The rods are longer and more 
slender, 2-4 n across and 40 60 m long. They are crowded 
about as closely together as is possible, so that the distance 
from centre to centre of the elements is not much greater 
than the diameter of the single element. In both the rods 
and the cones can be distinguished an outer section and an 
inner section. Just at the base of the cones and a little 
distance away from the rods is a swelKng that corre- 
sponds to the cell-body of the neurone. The axones of 
the rods and cones come into contact with the dendrites 
of the bipolar cells, and the axones of these in turn with the 
dendrites of the large gangHon cells. In the fovea it is said 
that a cone connects with a single bipolar cell and that in 
turn with only one gangHon cell. Thus the impulse from 
each cone in the fovea is kept separate all the way to the 
brain. In other portions single bipolar cells make connec- 
tions with more than one rod or cone. In addition to these 
direct lines of connection with the central nervous system, 
there is a layer of cells between the rods and cones and the 
bipolar cells which serves to connect different rods and cones 



THE STRUCTURE OF THE RETINA 105 

horizontally. It is possible, even probable, that some of the 
spreading of impulses in contrast and irradiation takes place 




Fig. 40. — Section of the retina, showing the neurones. (After Cajal, from How- 
ell's "Physiology.") 

over these horizontal cells. In addition to these nerve cells, 
throughout the retina are found supporting cells of non- 
nervous tissue, the so-called Miiller cells. In the innermost 
layer are fibres, the axones of the ganghon cells, which unite 



io6 FUNDAMENTALS OF PSYCHOLOGY 

to constitute the optic nerve and carry impulses to the cere- 
bral nervous system. 

Fovea and Blind Spot. — Certain parts of the retina show 
modifications from this general arrangement that make 
them of particular interest. One of these, the fovea, Hes 
near the centre of the retina. It is the point of clearest 
vision, the point turned towards objects we desire to see 
distinctly. As its name impKes, it is a pit or depression in 
the retina made by a drawing apart of the front coats of the 




Fig. 41. — Section of the fovea. It may be seen that the axones of the cones 
extend toward the periphery to make connection with bipolar and ganghon cells. 
On the left may be seen the central cells to which the visual impulse is carried. 
F, fovea; A, B, b, cones; a, rods; c, d, bipolar cells; D, E, ganglion cells. This 
section is inverted as compared with Figs. 39, 40. (From Cajal.) 

retina. This pit is due to the fact that axones which lead 
off from the cones go towards the periphery of the fovea, 
and the bipolar and ganglion cells with their axones and the 
blood vessels which supply the region are to one side of the 
cones rather than in front of them, — between them and 
the Hght, — as in other portions of the retina. The cones are 
here nearest the surface, and Hght need not pass through so 
much retinal tissue. In the fovea, too, are found only cones, 
and these are as long and slender as rods, so that the centres 
are only about 2-4 m apart. In the neighborhood of the 
fovea the retina has a yellowish tinge. The fovea is 0.3-0.4 
mm.; the rod-free area about 0.8 mm. in diameter. The 



RODS AND CONES ARE ORGANS OF VISION 107 



yellow spot is larger, 1-3 mm. in diameter. In psycho- 
logical writings the fovea, point of clearest vision, and yel- 
low spot are used almost interchangeably. This is only 
approximately accurate, as the dimensions of the yellow 
spot and fovea show. As one proceeds from the fovea, the 
rods become relatively more numerous, the cones less nu- 
merous, until at the periphery the cones are almost entirely 
lacking. Another region that deserves special mention is 
the bhnd spot, the area at which the optic nerve leaves the 
eye. This contains no rods or cones, but only the fibres, 
axones of the large ganglion cells, which unite to form the 
optic nerve. It is an area about 1.5 mm. (4°-6°) in diameter, 
about 5 mm. (15°) to the nasal side of the fovea. 

The Rods and Cones are the Organs of Vision. — There 
is very good evidence that the rods and cones are the organs 
of vision, i. Vision is absent where the rods and cones are 
lacking at the en- 
trance of the op- 
tic nerve. 2. The 
shadows of the 
blood vessels in 
the outer coat of 
the retina may be 
seen under suit- 
able conditions, 
and H. Muller 
has measured the 
distance of these blood vessels from the perceiving organs 
by a method of triangulation based on the apparent 
displacement of their shadows with known motion of the 
Light outside. He found that the blood vessels were from 
0.17-0.33 mm. from the perceiving coat, and measurements 
showed that the actual distance in the retina between blood 





Fig. 42. — Optogram, i shows the normal appear- 
ance of the rabbit's retina; 2 shows the condition when 
the rabbit has been permitted to look at the window of 
the dark room and then is killed while still in the dark 
and the retina fixed as a photographic negative is fixed. 



io8 FUNDAMENTALS OF PSYCHOLOGY 




vessels and the layers of rods and cones was from 0.2 and 
0.3 mm. 

The problem as to what changes go on in the retina when 
it is stimulated, what actually makes one see, has aroused 
much discussion. Two changes can be seen to take place. 
One is a change in the color of the pigment in the rods. The 
-^ retina of a frog killed in the light has 
a very light color. If, however, it be 
killed after being kept a long time in 
the dark, the rods have a dehcate 
purple hue. Pictures may be taken 
with the retina of a rabbit. If the 
rabbit looks for a little time at the 
window of a dark room in which it is 
placed, then is killed and the retina 
fixed as one would fix a photographic 
plate, a picture of the window can 
be seen on the retina. Such an opto- 
gram is shown in Figure 42. It has 
also been demonstrated by a similar 
method that the cones contract in a 
bright light. Between the choroid and the retina is a layer 
of large pigment cells regarded by some authorities as be- 
longing to the choroid, by others as an independent inter- 
mediate coat, and by still others as a part of the retina. 
These large hexagonal cells, Kke the black paint on the 
inside of a camera, insure the absorption of errant Kght rays. 
When the eye has been for a long time in the light, the cells 
are well down in the outer coat of the retina, and adhere to 
it. In the dark-adapted eye, on the other hand, they are 
well outside and come away from it freely when the 
choroid is stripped off. Of these changes only the bleaching 
of the visual purple has been given any meaning, and that, 



Fig. 43. — Showing posi- 
tion of pigment cells. In the 
dark - adapted eye (right) 
they are outside of the outer 
layer of the rods and cones; 
in bright-adapted eye (left) 
they are well down between 
the rods and cones. (From 
Siven and Wendt.) 



THE COLOR PYRAMID 109 

as we shall see, acts only as a sensitizer of the retina. 
(The positions may be compared in Figure 43.) 

Sensations of Light 

The Qualities of Vision. — All theories of vision have been 
based upon a study of visual phenomena rather than on a 
study of the physiological processes. Knowledge of physi- 
ological processes develops from a study of the laws of 
sight rather than the other way round. The sensations 
from the eye may be divided into four different series. The 
first is the series of pure spectral colors, which range from 
red to violet. These are paralleled by the changes in wave 
length, and change in wave length may be regarded as the 
cause of change in hue. The second is the brightness or 
achromatic series. It corresponds to the changes in the 
intensity or ampHtude of the vibration, provided the wave 
lengths are suitably mixed. The sensation series ranges 
from black to white through the grays which are interme- 
diate. The third series accompanies change in the intensity 
of a single wave length and ranges from the most saturated 
or complete color to black at a slight intensity of stimulus, 
and again from the most saturated color to a whitish hue, 
at the maximum intensity. The fourth series corresponds 
to the mixture of a single wave length with grays of the 
same intensity. The sensations that result range from the 
pure color to a gray. The amount of the admixture deter- 
mines what is called the degree of saturation of the color. 
The pure color is saturated, and the greater the amount of 
gray, the less the saturation. The last two variations are 
frequently mixed; saturation and brightness frequently 
change together. 

The Color Pyramid. — The four series have been repre- 
sented schematically by a double pyramid (Fig. 44). The 



no FUNDAMENTALS OF PSYCHOLOGY 



four primary colors red, yellow, green and blue are at the 
corners of the central square, with the intermediate pure 
spectral colors between. The oranges on the line between 
red and yellow, the yellow greens between yellow and green, 

and so on. At the bottom is 
black, and at the top white. 
The Hnes joining the square with 
the top and bottom represent the 
tints and shades. When a red 
wave is increased in intensity 
above the point of saturation, 
pink, a tint, is seen; when di- 
minished, brown, a shade, is per- 
ceived. The central Kne that 
connects black with white repre- 
sents the series of grays. The 
various degrees of saturation are 
represented by Hnes on the base 
of the pyramid from the outer 
square, where Lie the spectral 
colors, to the centre that repre- 
sents the neutral gray. The 
color tones are more and more 
mixed with the neutral tint from the circumference in- 
ward until color altogether disappears in the centre. 
The fact that the color may be mixed with a gray of 
greater or less brightness and so reduced in saturation 
and changed in brightness at the same time, can be repre- 
sented on the pyramid by lines from the base of our double 
pyramid to a point on the central line at any distance above 
or below the base. That the spectral colors are of different 
brightnesses has been represented by tilting the square base 
more or less, making the yellow corner higher than the 




Fig. 44. — Color Pyramid. 
(From Titchener's "Textbook of 
Psychology.") 



COLOR MIXTURE iii 

blue. We shall treat each of these series of sensations 
separately as far as possible. 

Hue. — We may begin with the colors of the spectrum. 
The spectrum is a continuous series of colors which shade 
one into the other with no breaks readily observed at the 
first glance. The one fact that has been emphasized by 
direct observation is that there are certain turning points 
in the apparently continuous series, points where one 
quahty gradually disappears and another gradually begins 
to show itself. Thus, at the long-wave end, red predomi- 
nates. As one moves the eye toward the short-wave end, 
red gradually becomes less and less pronounced until it is 
finally lost at 588 X in the yellow, which has also been pres- 
ent in some degree from the beginning. When red dis- 
appears, green begins to appear and gradually increases. 
In the meantime yellow gradually diminishes in amount 
until it disappears at 526 X and blue takes its place. Still 
another of these critical points occurs farther on at 484 X, 
where the green disappears and is replaced by the red of the 
violet colors at the short-wave end. 

Color Mixture. — The terms we have used imply that 
there are in the spectrum relatively few simple colors and 
that any two of these may be distinguished in the inter- 
mediate colors. All theories, ancient and modern, have 
been an attempt to discover just what these simple colors 
are, and to determine how they combine to produce the 
other colors. The fi.rst experimental indication of the fact 
that most colors are compound is obtained from color mix- 
ing. Colors may be mixed, either by having two different 
wave lengths of Hght fall upon the same spot of the retina 
at the same time, or, more conveniently, by rotating disks 
of the colors to be mixed so rapidly that one color appears 
[before the effect of the other has disappeared. Both 



112 FUNDAMENTALS OF PSYCHOLOGY 

methods give approximately the same results. ( The first 
law of color mixture is that two spectral colors when mixed 
give a color that lies between them in the spectrum. When 
the colors He near together, the resulting color approaches 
saturation ; the farther apart the two colors in the spectrum, 
the less is the saturation. Not only may we obtain spectral 
colors from the mixture of spectral colors, but, if different 
proportions of the extreme ends of the spectrum be mixed, 
colors are produced that correspond to no single wave 
length but are nevertheless true color tones of a high degree 
of saturation. These are the purples, mauves, and other 
similar qualities. Since they grade from red to violet, they 
may be regarded as filling the gap between the two ends of 
the spectrum. For sensation, then, the series of colors can 
best be pictured as a closed figure rather than as a straight 
line. The direct psychological evidence for this is that the 
two ends of the spectrum are more alike than are points 
nearer together. Violet has a greater similarity to red than 
has any spectral color beyond pure yellow, and the two ends 
of the spectrum may be joined by suitable mixtures of the 
extreme colors. 

The Primary Colors. — All agree that the colors we see 
in the spectrum are due to the stimulation of relatively 
few processes in the retina. These colors which may be 
regarded as pure are called primary. What the simple 
processes are has been in dispute between two opposing 
groups of theories. One, represented by Young, Helm- 
holtz, and their followers, uses the facts of color mixing as 
a criterion and so chooses three, the smallest number of 
colors that will give all of the other hues by mixing, and 
of the possible groups of threes, selects those that produce 
all of the others in the maximum of saturation. These are 
red of the end of the spectrum, green of approximately 



THE PRIMARY COLORS 113 

526 X, and blue or violet 475-430 X. For these three-color 
theories, yellow is a compound of green and red. A theory 
that would make four primary colors the basis for the 
composition of the spectrum was suggested first by Leonardo 
da Vinci and has received support on the more physiological 
side by Hering. Hering's four colors also, when combined, 
give the spectrum and in even greater saturation than the 
three colors. He chooses a red which is a combination of 
a Httle blue with the spectral red, a yellow of 575 X while 
the green is of 495 X and blue of 471 X. The spectral values 
for red and green in particular are relatively uncertain 
since they vary somewhat for different observers. But it 
will be noticed that the green is of a considerably shorter 
wave length for Hering than for Helmholtz. Helmholtz' 
green would be a yellow green for Hering, while his red 
would be a yellowish red. Hering states that the reason 
that Helmholtz asserted that red and green combine to give 
yellow was because Helmholtz chose both red and green 
with a yellowish hue, and when mixed red and green cancel, 
leaving the yellov/ predominant. 

That the spectral colors are derived from a relatively 
small number of simple colors seems demonstrated, first, 
by the fact that colors similar to those produced on the 
retina by single wave lengths of Hght can also be excited by 
stimulating the retina with two different wave lengths 
suitably chosen ; and secondly by the fact that the purples, 
which physically are always mixed colors, seem just as true 
colors as those produced by a single wave length. Irrespec- 
tive of the number and character of the simple colors, it is 
assumed by all theories that there are separate substances 
or processes in the retina for each of the primary colors, 
and that these simple structures or processes combine their 
effects in some way in the production of composite colors. 



114 FUNDAMENTALS OF PSYCHOLOGY 

It is further asserted that other than the primary colors 
aroused by single wave lengths are really mixed colors, 
physiologically. Thus blue-green in the spectrum produced 
by a single wave length is physiologically compound, due 
to the simultaneous action of the blue and the green organ 
or process. 

The Nature of White Light. — A second law of color 
mixing is that certain spectral colors when mixed in the 
right proportions produce, not an intermediate color, but 
a colorless sensation, a gray, whose shade depends upon 
the ampHtude of the light waves. Colors which cancel each 
other in this way are called complementary colors. This 
brings us to a consideration of the physical nature of white. 
Hght with its darker tones of gray and black. There are no 
single wave lengths that give rise to these brightnesses. 
They are produced only when certain properly chosen 
combinations of wave lengths affect the retina. In the sun- 
Hght all the colors of the spectrum are present, but the result 
for sensation is a somewhat yellowish white, owing to domi- 
nance of the yellow Kghts. 

Complementary Colors. — To produce white, the simple 
wave lengths must be present in the right number and pro- 
portion. Both theories assume that white or gray Hght is 
produced when all of their primary colors are present in 
the proper balance. For Helmholtz all must excite the 
retina at the same time, while Hering asserts that white is 
seen whenever both components of either of his comple- 
mentary pairs of simple colors are active in the same degree 
— when red combines with green or yellow with blue — 
and that they are all present in the spectrum in almost the 
proper balance to neutraHze each other. This explains the 
fact mentioned in connection with the first law, that spec- 
tral colors when mixed do not give a saturated color and 



SENSATIONS OF COLOR 



115 



that the farther apart they are in the spectrum the less 
saturated they become. Colors farther apart are more 
nearly complementary, and so more white is present in the 
compound. The hst of wave lengths of colors that are 
complementary is given in Table I. It will be seen that 
no simple statement can be made of the relation of the 
wave lengths of complementary colors. Each must be 
determined for itself. As a result of the facts stated in 



Table I. — Table of Complementary Colors for Two Observers 




this law it may be asserted that each color has a comple- 
ment, that all colors go in pairs, although the colors in the 
middle of the spectrum have non-spectral colors as their 
complements. In terms of the four-color theory each pri- 
mary color has a complement — green is the complement 
of red, blue of yellow. As each combination of two colors 
is made up of two simple colors, there is always a second 
combination of two colors, each complementary to one 
member of the first pair, which when mixed give gray. 

Color Blindness. — The phenomena of color bhndness 
offer much aid to an understanding of color vision. Some 



ii6 FUNDAMENTALS OF PSYCHOLOGY 

three to five per cent of men and a much smaller percentage 
of women are found by tests to be unable to distinguish red 
and green. To them certain reds and greens look exactly 
alike. When the proper changes in brightness are made, 
red and green papers look gray and all three may be con- 
fused. The fact of confusion has been noted for a long time. 
The chemist Dalton furnished one of the first instances 
recorded, and for a long time the defect was known as 
Daltonism. It is only recently that fairly general agree- 
ment as to the explanation has been reached. Young and 
Helmholtz and their followers were of the opinion that one 
might be bhnd to only one color, one might be red-blind or 
green-bhnd, or both. Studies by Von Kries and others who 
were originally pupils of Helmholtz convinced them, how- 
ever, that on the whole Hering was right in his statement 
that when one of a pair of complementary colors could not 
be seen, the other was also wanting. In brief, the red-blind 
individual is also green-bhnd and sees both colors as grays. 
Still rarer are the cases in which the sufferer sees no colors, 
but only grays. One other case is rarest of all in which the 
patient is blue-yellow bhnd, and can see red and green, but 
not blue or yellow. 

Peripheral Vision. — Closely related to the phenomena 
of color bhndness is the vision on the peripheral retina of the 
normal eye. It may be said that every eye has in it a red- 
green bhnd area and a totally color bhnd area. If one will 
look at any color out of the side of the eye, it will be seen 
that the colors undergo a marked change. One can see the 
full range of colors only for twenty or thirty degrees from 
the fovea; the distance varies with the individual and with 
the diagonal that is used. Beyond that one can see no reds 
or greens, but for ten degrees or so farther blues and yellows 
alone. Beyond that grays only are perceived. The field of 



SENSATIONS OF COLOR 117 

vision for colors and for grays extends much farther on the 
temporal side and below than on the nasal side and above. 
Different experiments will not ordinarily show that members 
of the same pair of colors vanish sharply at the same point, 
since the point of disappearance depends upon the size of 
the colored surface, upon the saturation and tone of the 
color, upon the brightness of the color, and upon its con- 
trast with the background, and care must be taken to obtain 
standard stimuh and conditions. When all the colors used 
have the same values in these respects, the colors vanish by 
pairs as indicated above. 

These facts of color bhndness and of peripheral vision 
indicate that the four primary colors are closely joined in 
pairs. A study of the colors that remain to the color bhnd 
and of the way colors vanish on the periphery of the eye is, 
then, an important aid in determining which are the 
primary colors. That there are four colors rather than three 
becomes evident from the fact that first red and green dis- 
appear and then yellow and blue. 

Negative After-images. — Two other subordinate phe- 
nomena emphasize the opposition between these pairs of 
colors. These are the negative after-image and contrast. 
One may obtain a negative after-image if one looks for sev- 
eral seconds at any color and then for a couple of seconds 
at a neutral surface. The negative after-image is a fainter 
patch of the complementary color which gradually makes 
its appearance upon the neutral surface and remains 
for several seconds. The length of time that it lasts 
depends upon the intensity of the original color, upon its 
duration, and the extent of the surface stimulated, 
and upon the degree of fatigue of the eye. If two primary 
colors are present in the inducing stimulus, the complement 
of each will be present in the after-image. Thus purple 



ii8 FUNDAMENTALS OF PSYCHOLOGY 

gives a yellow-green after-image, and orange, a greenish- 
blue after-image. The complete explanation of this phe- 
nomenon can best be discussed in connection with the theo- 
ries of color. We may be content here to regard it as an- 
other indication of the fact that complementary colors 
stand in a very close relation to each other. 

Contrast. — The laws of contrast may be stated in terms 
very similar to those used for the after-image, different from 
it only in that one relation is spatial, the other temporal. 
One has been called successive, the other simultaneous con- 
trast or induction. Wherever a color stimulates the retina, 
a complementary color is induced in the surrounding area. 
The brightness of the induced color and the size of the halo 
depend, again, upon the brightness of the color, its size, and 
upon the similarity in brightness between the color and its 
background. Contrast colors can be seen most easily if a 
colored Hght and a white Hght are admitted to a dark room 
and a rod casts a gray shadow on the colored surface. The 
shadow will appear in the complement of the color. Thus 
shadows on the grass are purple, those on the snow in yel- 
low sunshine are blue, etc. A gray strip of paper on a col- 
ored surface also takes on a color complementary to the 
paper, but it is not so easily seen by the beginner. If one 
will cover the entire surface with tissue paper, the contrast 
color comes out clearly. In general, the rule holds that the 
less definite the contour between the inducing and the 
induced color, the more definite the contrast. The indi- 
vidual has become so accustomed to seeing contrast colors 
that he forms the habit of allowing for them and sees the 
objects in the colors that they would have, were they alone. 
He has learned that a gray strip of paper looks red on a green 
background and sees the gray that is known to be the real 
color of the paper in spite of its appearance. The tissue 



THE ACHROMATIC SERIES 119 

paper makes it difficult to be sure that the gray strip is 
really a separate object on a colored surface, the habitual 
interpretation is not appHed, and the contrast color that is 
really present on the retina is seen. 

Summary of Facts of the Chromatic Series. — Of the 
pure spectral colors we may assert that all are combined 
from four primary colors, — red, green, yellow, and blue 
— and that these four colors are paired in most of their 
activities, red with green, and yellow with blue. Each 
when mixed with its complement gives gray. In color 
bhndness and on thfe peripheral retina, red and green, yellow 
and blue, disappear together. When one of these colors 
stimulates the retina, its complement appears in the after- 
image. The complement also irradiates from its surface, 
giving the contrast color. 

The Achromatic Series. — The achromatic series is less 
rich in sense quahties. It contains only the series of grays, 
ranging from black to white. There are no breaks or turns 
in it as in the color series. Like the color series it shows 
the phenomena of positive and negative after-images, of 
contrast, and of mixture, in so far as two grays when mixed 
give an intermediate shade. The physical conditions of 
seeing the achromatic series are imphed in the name. 
Whenever colors are eliminated in any way, the gray alone 
is seen. There are five conditions under which this eUmina- 
tion may be brought about: by combining colors in pairs 
of complements, discussed on page 114; by reducing the 
intensity of the Kght; by reducing the size of the area 
affected; by reducing the time of stimulation; by stimu- 
lating with any wave lengths the periphery of the retina 
or a totally color bhnd retina. These facts indicate that 
there is a different organ for brightness and that this organ 
is stimulated in isolation whenever the color processes 



I20 FUNDAMENTALS OF PSYCHOLOGY 

cancel ; when the light is too faint to arouse the color organs, 
but will still stimulate the brightness organ; when the 
duration is too short to arouse the color processes; and 
where the color organs are absent as on the periphery and 
in the color blind eye. 

The Duplicity Theory. — Within the last generation, 
evidence has accumulated that there are two organs of 
brightness instead of one. One of these is in the cones; it 
senses the brightnesses of moderate intensity. The other is 
in the rods, is more sensitive, and appreciates the bright- 
nesses in faint lights. It is possible to compare the effects 
of stimulation of the two organs, from the fact that the 
fovea has cones alone, and also because of the greater 
sensitiveness of the rods. Three facts may be adduced as 
evidence of the difference in function of rods and cones. 
First the rods are more sensitive to faint Hghts than are 
the cones. Second, the rods respond to all wave lengths 
by brightness alone, while the cones respond to different 
wave lengths with different colors. Third, the rods are 
more sensitive to the short wave lengths, the cones to the 
long wave lengths. We shall consider each of these phe- 
nomena separately. 

Adaptation in Faint Light Vision. — The most striking 
phenomenon of adaptation is the great increase in sensitivity 
of the retina after a period in the dark. After an hour 
in the dark the eye is about loo times as sensitive as it is 
in ordinary day Hght indoors and from 100,000 to 150,000 
times as sensitive as it would be after a long period in the 
bright sunHght. Adaptation continues for as much as 
sixteen hours, but is most rapid in the first few minutes and 
is relatively sHght after the first hour. It is probably due 
in very small part to the expansion of the pupil, but for 
the greater part to the visual purple which regenerates 



DISSAPPEARANCE OF COLOR 121 

after a time in the dark, and by some chemical action 
increases the sensitivity of the chemical substances in the 
rods. The fovea in an area of about two degrees in diam- 
eter shows Httle adaptation to the dark. It undergoes a 
quick adaptation for two or three minutes and then remains 
constant. In the dark-adapted eye the most sensitive 
point on the periphery according to Nagel may be 1000 
times as sensitive as the fovea. In day light adaptation the 
fovea is 20-40 times as sensitive as the periphery. It is 
for this reason that one can see a faint star better if one 
does not look at it directly but sees it out of the corner of 
the eye. Adaptation is almost entirely restricted to the 
rods. 

Disappearance of Color with Reduction of Illumination. 
— The most noticeable difference between the spectrum as 
seen at the intensity of ordinary day light and in the faint 
light of a dark room is that the colors are altogether lacking 
at the low intensities and the spectrum appears as a band 
of gray Hght. As the intensity is diminished, the colors 
disappear in different orders. The reds and violets vanish 
first and the orange is the last to go. Mixed colors change 
their hue with the reduction of the Hght. Scarlet becomes 
orange, orange, more yellow, and blue-green shifts towards 
blue. With the exception of extreme red, the colors are 
seen as brightnesses after they disappear as color. Blue 
has the longest of these colorless intervals. This so-called 
'photo-chromatic interval' is not present at the fovea. 
There the colors are not seen as grays after they cease to 
stimulate the retina as colors. This leads us to believe that 
the colors are seen by the cones alone; brightnesses of low 
intensities are seen by the rods. Where the rods are 
lacking there is no gray that persists after the colors 
cease to be seen. 



122 FUNDAMENTALS OF PSYCHOLOGY 

The Purkinje Phenomenon. — The evidence from the 
change in brightness of different parts of the spectrum with 
diminution of intensity is quite as marked. If a red and a 
blue seem of equal brightness in ordinary day Hght, the blue 



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Hght for two protanopes, S and M, and for two deuteranopes, 5/ and A'. (From 
von Kries.) 

will be much brighter in reduced illumination. The short 
wave lengths have a much greater effect upon the rods 
which are active in the faint Hght. In this they stand to 
the cones much as the photographic plate, which registers 
the shorter waves but not the red, to the eye as a whole. 
In day light the brightest point in the spectrum is in the 



COLOR BLINDNESS 123 

yellow X 600 ca., while in faint light the brightest point 
shifts well towards the green X 540 ca. This shift is known 
as the Purkinje phenomenon. The Purkinje phenomenon 
also appears in the comparison of single colors. If a red 
and a blue are equally bright in day light, the blue will be 
markedly brighter in a faint light. This effect shows even 
where the lights are combined in a gray which altogether 
disguises the color. If one gray be mixed of long wave 
lengths, red and green, and another of blue and yellow and 
these grays be made of equal brightness in day Hght, the 
gray compounded of long wave lengths will be much 
darker in faint light. It should be said that in hght suffi- 
ciently faint to give the Purkinje phenomenon, the colors 
will not be seen as colors, but merely as brightnesses. The 
spectrum in faint light is a band of gray with a relatively 
bright spot where the green would be in bright Hght. That 
the faint light spectrum is seen with rods alone is evident 
from the fact that it cannot be seen with the fovea. These 
three phenomena — different adaptation in periphery and 
fovea, the lack of color in faint Hght, and the Purkinje 
phenomenon — are all to be explained on the assumption 
that both the rods and the cones give gray, but are differ- 
ently sensitive to long and short waves. The grays are of 
approximately the same quality. The only difference 
noticed is that according to von Kries the gray from the 
rods has a sHghtly bluish tone. 

The Different Forms of Color Blindness. — The distinc- 
tion drawn between day Hght and twiHght vision, or cone 
vision and rod vision, has proved very fruitful in the inter- 
pretation of certain facts of color bHndness. In the long 
controversy between Hering and Helmholtz a standing point 
of discussion was as to whether there was ever bHndness 
to red without also bHndness to green. Hering insisted that 



124 FUNDAMENTALS OF PSYCHOLOGY 

bKndness to one was always accompanied by blindness to 
the other. Helmholtz regarded red and green as independ- 
ent colors and asserted that one might be bhnd to either 
alone. Observations seemed ambiguous. Most cases saw 
only blue or yellow, but occasionally careful examination 
indicated that red would be seen more clearly than the 
green. When the twilight or rod vision was discovered, it 
was soon found that in the eye of the totally color bhnd 



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Fig. 46. — Brightness of prismatic spectrum of gas light for total color blind 

, and for twilight vision of normal eye — ■ — . Comparison with Fig. 45 shows 

that both have the same value as the protanope. (From von Kries.) 

only the rods were active. The patient could see much 
better in twihght than in ordinary day hght, the relative 
brightness of spectral waves was the same as that of the 
normal individual in twihght, and it was shown in a number 
of cases that he was totally blind in the fovea, where, as has 
been said, there are no rods. In certain cases the blindness 
in the fovea was not noticed, but von Kries argues that this 
was probably due to the difficulty in making observations. 
Not all would agree that every case of total color blindness is 
due to lack of function of the cones, but certainly many are. 



COLOR BLINDNESS 



125 



In the application of this discovery to the cases of partial 
color blindness, measurement of the brightness values of a 
number of individuals indicated that the difference between 
the two types, called by Helmholtz the red-bhnd and the 
green-bhnd, could be traced to the dominance of twilight 
brightness values, or to the dominance of day Hght values. 
Both types were defective in both red and green, but as 
the red-bhnd saw the spectrum, the long wave lengths were 
much darker and so the reds were not noticed. For the 
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Fig. 47. — Brightness of the gas light spectrum for the periphery of the normal eye 
, and for protanope . (From von Kries.) 

were more Hkely to see the reds than the greens. To avoid 
the ambiguities of the older terms von Kries has suggested 
that those individuals who see the spectrum in the relative 
brightness values of normal individuals in day Hght be 
called deuteranope, those who see it in twihght values 
shall be called protanope. The brightness values are the 
same for the protanope, for the totally color blind, and for 
the twihght vision of the normal eye. On the other hand, 
the brightness values of the spectrum are also the same for 
the deuteranopes, the normal eye in day Hght, and the pe- 
riphery of the normal eye, as may be seen from the accom- 
panying charts from von Kries (Figs. 46, 47). All this 



126 FUNDAMENTALS OF PSYCHOLOGY 

argues for two kinds of brightness vision, one by the cones, 
the other by the rods. While the actual sensations of gray 
given by the two are not to be distinguished, the secondary 
characteristics are markedly different. 

Temporal Phenomena of Vision. — The characteristics 
of a color depend in many ways upon the duration of the 
color stimulus. StimuH do not produce their maximum 
effect at once, nor does the color cease at once with the 
excitation. There is always a rise to full effect and a gradual 
disappearance. The course, as has been shown by Miss 
Bills, is different for each of the colors, both for the period 
required to attain its maximum, and for the period of 
decHne. The curve varies for each color and for the differ- 
ent intensities of the color. At the lowest intensity used, 
the order was yellow, red, green, and blue; for the medium 
intensity it was yellow, green, blue, red; and for the highest 
intensity, yellow, red, green with blue undetermined. ^ 
These results were obtained in the dark. They may be 
different for dayhght conditions. When the sensation 
reaches its maximum, even when the stimulation persists, it 
begins at once to diminish its intensity, at first rapidly, and 
then very gradually until all colors disappear. This gradual 
loss of color, called adaptation, can be easily demonstrated 
if one will but gaze fixedly at a small "square of color. The 
disappearance of the color of the glass when colored glasses 
are worn illustrates the same phenomenon. Black and white 
also show the same tendency. The rate of adaptation varies 
with the color, so that one component after another may 
vanish. 

After the stimulus is removed, the excitation continues 
for a moment to be of the same quality as the original, and 

1 Bills, The Lag of Visual Sensation. Monograph Supplement of the 
Psychological Review, vol. 28. 



TEMPORAL PHENOMENA OF VISION 127 

then gradually dies out. This persistence is called the 
positive after-image. The dying out corresponds to the 
period of rise of stimulation. Both may be regarded, and 
are regarded in all theories, as an expression of the inertia 
of the color processes. They require time to start and to 
stop. For a fraction of a second the color or gray persists 
in approximately full brightness. It is this fact that makes 
possible the mixture of colors on rotating disks. The excita- 
tion of one color persists during the excitation of the retina 
by the other. For practical purposes the effect is the same 
as if both Hghts were active at the same time, and the 
brightness effect produced is the average of all the Kghts 
that are stimulating the eye during the period. If the 
rotation is less rapid, one obtains a rapid fluctuation in 
brightness, the flicker. This flicker disappears at a lower 
rate of rotation when cplors are of the same brightness 
than when they are of different brightnesses. This fact 
makes it possible to compare directly the intensity of differ- 
ent colored Kghts, a problem that produces difficulties for 
ordinary photometric methods. 

Aside from this positive after-image, if one gives but a 
single stimulus of relatively short duration, it will be 
noticed that there are at least two other images succeeding 
the first. After a momentary dark period there comes a 
complementary after-image, usually with an added slightly 
bluish hue. After another dark interval, an image of the 
same color as the first and usually fainter appears, to be 
followed by another dark period. Including the dark 
periods which look like black it is possible under favorable 
conditions to see six different images following a colored 
sector on a slowly rotating disk. These images are an ex- 
pression of the fact that the retina responds rhythmically, 
that when a retinal excitation is started it rises and falls in 



128 FUNDAMENTALS OF PSYCHOLOGY 

its response in a regular order. The second of the images 
mentioned above is assumed to be due to the delayed exci- 
tation of the rods, the third to a renewal of the excitation 
of the brightness organ of the cones. 

Interesting also is the fact that it is possible to excite 
colors as an after-effect of brightness. If one will look for 
half a second or so at the setting sun and then for a time 




Fig. 48. — Benham disk. 

watch the after-image as projected against a neutral surface, 
one will observe a slow succession of colors and grays that 
will last for several minutes. Helmholtz gave the order, 
with the eyes open, as white, red, green, red, blue. One 
notes in this, too, that the color of an image depends upon 
the character of the background. It will have a different 
color with the eyes open and with the eyes closed. When the 
eyes were closed, Helmholtz found the order to be blue, 
green, yellow. It will also be noticed when a black and white 
disk is revolving slowly that a series of faint colors seems 



SPATIAL PHENOMENA OF VISION 129 

to follow the edge of the black sector. Similar, too, in 
explanation is the color produced when a white disk with 
concentric rings of black is rotated. If a disk similar to 
that in Figure 48 is rotated slowly, the inner ring appears 
purplish, the outer greenish. The explanation of all these 
phenomena is somewhat uncertain, but seems to fit best 
with the assumption of Helmholtz that in some way the 
color processes are excited by the black and white and that 
the different colors die out at different rates and so one 
color will predominate at one time, another at another. 

The Spatial Phenomena of Vision. — It has been shown 
that the visual excitation is not limited to the actual dura- 
tion of the stimulus; its influence is similarly not limited 
to the area stimulated, but extends about it in all directions 
to varying extents. A series of facts can be adduced to 
demonstrate this. 

1. Bright colors always look larger than dark ones. A 
white square on a black ground always looks larger than a 
black square on a white ground. In each case the white 
stimulus spreads at the expense of the black. Still more 
striking is the apparent increase in the size of the filament 
of the electric Hght when it glows as compared with its size 
when cold. 

2. A number of small surfaces of two or more colors 
when in juxtaposition fuse into a color identical with that 
given by the same colors when mixed by rotation. Each 
color extends beyond the area stimulated, and these exten- 
sions overlap to produce a continuous color of the average 
hue and brightness of all. The overlapping in space is 
similar to the overlapping in time in mixtures produced by 
rotating disks. In many fabrics it will be noticed that the 
dominant color seen at a distance is a mixture of a number 
of threads of different colors 



I30 FUNDAMENTALS OF PSYCHOLOGY 

3. A colored surface may be too small to be seen as 
colored and may yet be seen as gray. Colored objects at a 
distance lose their color while still visible. The size at which 
the color disappears varies for different colors. The table 
below gives the diameter of five colors at which the surface 
will be seen as gray in the first column and at which it will 
be seen in color in the second. The column headed " Ratio " 
gives the proportion between the areas that can be seen at 
all and the areas that can be seen as colored. It will be 
noticed that a red surface, which is large enough to be seen 
at all, is seen as red, while a much larger area of blue is seen 
only as gray. Several bits of color, each too small to be 
seen alone, will when close together induce a color sensation. 
The explanation is the same as for the second law above. 



COLORl 


Absolute Limen 


Color Limen 


Ratio 


Extreme red 


0.5 


I.O 


4 


Orange 


0.9 


2.1 


S-S 


Yellow 


I 


31 


9.6 


Green 


0.3 


4.2 


196 


Blue 


0-3 


7-5 


625 



4. In some degree, size, duration, and intensity are 
interchangeable. More intense lights seem larger, seem to 
last longer, and, vice versa, within limits larger surfaces and 
longer exposures seem to give more intense stimulations. 
Up to two minutes in size doubling the intensity doubles the 
apparent size. 

These various phenomena are to be explained by the 
spread of the effects of the excitation in the retina, either 
by a spread of the chemical effects from one unit to another, 
or by a spread of nervous impulses from the cones or rod 
stimulated to neighboring ones through the connecting 
neurones just inside the layer of rods and cones. (See 
p. 104,) Contrast is due to a similar phenomenon, but has 
^From Charpentier, Annales d'ocul. Ixxix, 1878. 



THEORIES OF COLOR 131 

been described above, and the explanation may best be left 
to the discussion of the various theories, as the induction 
of a complementary color introduces a new principle. 

The Helmholtz Theory. — A brief statement of the more 
important theoretical explanations of color may serve as a 
review of the facts. The first of the modern theories was 
formulated by Thomas Young, an English physicist, and 
expanded by Helmholtz. It assumes that there are three 
separate kinds of organs in the retina, that one of these is 
affected most strongly by red, another by green, and a third 
by blue or indigo. When all three are excited at once, white 
is produced. Red and green when stimulated together give 
rise to yellow. All the other colors are produced by the 
mixture of the effects of two or all three of the organs. After- 
images are due to the fatigue of some of the organs and the 
response of those remaining when white light falls upon the 
retina. Contrast is an illusion of judgment. The facts are 
out of harmony with the theory on all but one point. 
I . Yellow cannot be a compound color, since yellow may be 
seen where both its assumed components are lacking, on 
the periphery of the retina and by the color blind. 2. The 
same objections hold against regarding white as a com- 
pound. It, too, can be seen where no one of its components is 
present. 3. The explanation of after-images falls with the 
abandonment of the theory that white is a compound color. 
4. Contrast is not an illusion of judgment, as it is most 
easily noticed where one is not aware that the inducing 
color is present. The one remnant of the Helmholtz theory 
is its explanation of color mixing, and the colors that it 
chooses as primary do not meet any of the physiological 
tests. The modern adherents of the Helmholtz theory hold 
also that it explains color blindness, although they admit 
that the partially color bHnd see only blue and yellow. 



132 FUNDAMENTALS OF PSYCHOLOGY 

They add to the color processes the rods as an organ for 
brightness, but still assume that the grays in day Hght as 
seen by the cones are a compound of all three colors. 

The Hering Theory. — The Hering theory asserts that 
there are two pairs of primary colors with the elements 
in each pair opposed, and an independent brightness organ. 
The theory assumes that each pair of colors is produced by 
antagonistic changes in the same organ. One organ gives 
rise to red and green, a second to blue and to yellow, and a 
third to the brightnesses, black and white. The antagonistic 
processes are said to be anabolism and cataboHsm, the up- 
building of the organ and its deterioration. Green, blue, 
and black induce anabolism, the others catabolism. Com- 
plementariness is explained by the fact that members of 
the same pair of colors tend to induce opposed processes in 
the same degree and so produce no effect. When the ten- 
dency of green to produce anaboHsm and of red to cause 
catabolism are equally strong, no change in the organ re- 
sults. Since all wave lengths stimulate the brightness 
organ, gray is seen, and seen alone, when the colors cancel 
each other. Color blindness is due to an absence of one or 
more of the organs. The red-green organ is most frequently- 
lacking. Red-green bhndness is most frequent, and red 
and green are least widely distributed on the retina. In 
total color blindness the yellow-blue organ is lacking also, 
the white-black organ alone is present. Positive after- 
images are explained as due to a continued action of the 
organ after the stimulus has ceased. In the negative after- 
image anabolism is followed by catabolism, since the excess 
material accumulated by the retinal excitation tends to 
disappear as the Hght ceases to act and the tissues return 
to their normal balance. Similarly, cataboHsm is followed 
by anabolism when the stimulation ceases. Contrast is 



THEORIES OF COLOR 133 

due to one process inducing its opposite in contiguous areas. 
Excessive anabolism in a stimulated area is at the expense 
of the nourishment of the other adjoining areas, and cata- 
boHsm results there. 

Criticism of the Hering Theory. — The most important 
objection to the Hering theory is its assumption that the 
opposed processes are anaboHsm and cataboHsm. Nowhere 
in the bodily structures is anaboHsm induced by stimula- 
tion. If the exact change be left indefinite, be regarded as 
a rever^ble chemical process, as Miiller and von Kries have 
suggested, nothing would be lost in adequacy of explanation 
of the phenomena and much is gained in credibiHty. A 
second minor objection, made by Miiller, is that it is incon- 
sistent to assume that the opposed processes cancel each 
other in the color organs, while in the black- white organ 
they give a sensation, the neutral gray of the rested eye. 
Miiller suggests that the white-black processes cancel each 
other, so that when there has been no excitation for a long 
time the retina gives no sensation, but that the cortical 
cells, the central organ for vision, produce the gray. As 
evidence for this he cites the fact that the blind, if not 
bhnd from birth, always see this gray, and that a spot of 
gray is seen where even a small area of the retina has been 
destroyed. 

The Ladd-Franklin Theory. — A recent theory of Mrs. 
Ladd-Franklin gives an evolutionary theory of color vision. 
She assumes that primitive vision in animals is rod vision 
which gives differences of brightness only. Later cones 
develop and with them comes the appreciation of colors. 
Within the cones there is also a development. First appear 
substances sensitive to blue and yellow alone, then the sub- 
stance sensitive to yellow divides into two, one sensitive to 
red and the other to green. Each more evolved organ may 



134 FUNDAMENTALS OF PSYCHOLOGY 

act as a whole to give its original sensation. The cone 
when stimulated as a whole gives brightness, the red and 
green acting together give yellow. The color-blind eye is 
an undeveloped eye. In red-green blindness the yellow 
substance has not yet subdivided, in total color bHndness 
the cones act only as rods. While very ingenious, its choice 
of primary colors is open to certain of the objections to the 
Helmholtz theory, and it fails to recognize the differences 
between rod vision and cone vision as seen in the Purkinje 
phenomenon or to explain them in an adequate manner. 

We may emphasize certain essential facts which all 
accept. I. There are four primary colors, distinguished 
from the others by the fact that they vanish without change 
of quality as they are moved outward to the periphery. 2. 
These four colors are arranged in pairs, red with green, 
blue with yellow. The pairs cancel when mixed in suitable 
proportions; one induces the other as an after-image and 
excites the other on the surrounding areas of the retina. 3. 
There is an independent brightness which is present in all 
colors and is seen alone when the colors cancel each other, 
at low intensities of hght, and where the color organs are 
lacking. Physiologically we may assume an organ for each 
pair of colors. For this the Hering theory as modified by 
von Kries is as acceptable as any. That means a single 
organ for each pair and in each organ opposed chemical 
processes. The exact nature of the processes must be left 
undecided. To this must be added the acceptance of a dis- 
tinction between rods and cones as organs for brightness. 
They give the same sensations of brightness, but the rods 
are more sensitive absolutely and are also relatively more 
sensitive to the short wave lengths; the cones more sensi- 
tive to the long. 



THEORIES OF COLOR 135 

REFERENCES 

Parsons: Color Vision. 

Greenwood: Physiology of the Special Senses, pp. 86-214. 

Helmholtz: Handbuch der physiologische Optik, 3d Edition, 
Vol. II. 

VON Kries: Die Gesichtsempfindung. Nagel's Handbuch d. 
Physiologic, Vol. Ill, pp. 109-279. 

Myers: Experimental Psychology, Chs. VI, VII. 

Howell: Physiology, Chs. XVII, XVIII. 

Titchener: Experimental Psychology, Vol. I, Pt. II, pp. 1-50. 

Mrs. Ladd-Franklin : Article on Color, Dictionary of Phi- 
losophy and Psychology. 



CHAPTER V 
SENSATION {Continued) 

Audition 

The auditory sensations stand next to the visual, both 
in complexity and in importance for behavior and mental 
life in general. We can approach the study of audition in 
three different ways. Physically, sound is vibration in the 
air; physiologically, it is oscillation of some deHcate mem- 
brane in the ear; psychologically, it is the series of sensa- 
tions, the material of music and human speech on the one 
hand, and the series of noises and unorganized sounds on 
the other. The physical processes consist of longitudinal 
oscillations that proceed outward concentrically from the 
vibrating body. These oscillations vary in rate, which cor- 
responds to the pitch of the tone; in amplitude, which cor- 
responds to the intensity of the tone; and in complexity, 
which corresponds to the timbre, or tone-color. 

The Structure of the Ear 

The Divisions of the Ear. — The organ that translates 
these vibrations in the air into nerve processes is the ear. 
The ear is composed of three parts: the external ear, con- 
sisting of the pinna, commonly called the ear, and the 
external auditory meatus or tube that runs into the head; 
the middle ear, an enlarged cavity in the skull separated 
from the external by the membrane of the tympanum or 
drum; and the internal ear, a labyrinthine cavity between 
the middle ear and the brain where the vibrations are trans- 

136 



THE STRUCTURE OF THE EAR 



137 



lated into nervous impulses. The external ear needs no 
description. The outer ear probably has some influence in 
collecting the vibrations in the air and turning them into 
the external meatus. The meatus itself is curved slightly 
and thus reduces to a minimum the probabiHty of injury 
to the membrane of the tympanum. 

The important structures of the middle ear are the mem- 
brane of the drum, three small bones that stretch across 




Fig. 49. — Schematic section of the ear; .1/ and G, external ear; P, middle ear 
with small bones; S, cochlea; B, semicircular canal; A, auditory nerve; R, Eu- 
stachian tube. To give a sectional view the cochlea is displaced go°. Its apex 
should be turned toward the observer. (From Calkins, after Martin-Czermak.) 

the cavity of the middle ear, and the membrane which with 
the plate of the stirrup closes the oval window of the inner 
ear. The chain of bones consists of the malleus, incus, and 
stapes, named from their shapes, which resemble a hammer, 
anvil, and stirrup, respectively. The handle of the hammer 
is fastened to the inner surface of the membrane of the 
tympanum, the head is jointed into the top surface of the 



138 FUNDAMENTALS OF PSYCHOLOGY 

anvil, not unlike a large molar tooth in shape, and is hung 
by a ligament from the top of the cavity of the middle ear. 
The stirrup is attached by a deHcate cartilage to a process 
of the anvil, not unlike one of the roots of the tooth. The 




Fig. 50. — Tympanum and small bones seen from within the middle ear. i, an- 
vil; 2, suspensory ligament of hammer; 4, head of hammer; 7, tendon of tensor 
tympani; 8, foot-piece of stirrup that fits into the oval window; 10, handle of 
hammer or manubrium; 11, tensor tympani; 12, membrane of the drum; 13, Eu- 
stachian tube. 



membranes and the bones swing together on the ligament 
as a fulcrum. When the air vibrations impinge on the mem- 
brane of the drum, it swings inward, carrying the hammer 
and the other bones with it, and the foot of the stirrup 
pushes against the lymph of the inner ear, and sets that in 
vibration also. Two muscles prevent movements strong 
enough to rupture either membrane. One, the tensor tym- 



THE STRUCTURE OF THE EAR 



139 



Mcp 




Mm 



Fig. 
middle ear. 
S, stirrup. 



51. — The bones of the 
M, hammer; /, anvil; 



pani, extends laterally from a bony canal inside of the tym- 
panum and is inserted in the head of the hammer; the other, 

the stapedius, extends from a 

tube in the lower inner wall of 

the cavity and is inserted by a 

long Hgament in the head of 

the stirrup near where the 

anvil is joined to it. The two 

muscles oppose each other. 

The tensor tympani tends to 

draw the drum head inward, 

the stapedius to draw the 

stirrup foot away from the 

oval window toward the drum 

head. When both contract, 

the entire vibrating mechanism is held firm and prevented 

from making too violent oscillations. 

The membrane of the 
drum, by virtue of its coni- 
cal shape, the arrangement 
of the fibres that compose 
it, and the weighting on 
one side only, has no tone 
of its own, responds to all 
vibration rates impartially, 
and so transmits all tones, 
whatever their pitch, with 
approximately equal 
strength. In traversing 
Fig. 52. — Illustrates the way in which the middle ear, the ampH- 

the three bones act together as a bent j. j r . i • j 

lever, i, the handle of the hammer; tudc Ot the WEVCS IS dc- 

2 the long process of the anvil; 3, the creascd and their intensity 

stirrup; a-b, the axis of rotation. (From . . 

Howell's "Textbook of Physiology.") increased. Thls change 




I40 FUNDAMENTALS OF PSYCHOLOGY 




takes place in two ways. First the area of the oval window 
is much smaller than the area of the drum, so that the 
energy is more concentrated. Second, as can be seen in 
Figure 53, the lever arm formed by the handle of the ham- 
mer has a greater effective length than that formed by the 

process of the anvil to which 
the stirrup is attached. Sound 
waves, then, traverse the oscil- 
lating mechanism of the middle 
ear with rate or pitch un- 
changed but with intensity in- 
creased twenty to thirty times 
and with a corresponding di- 
minution in ampHtude. An 
essential mechanism for mak- 
ing possible the vibration of the 
drum and for protecting it 
against rupture due to differ- 
ence between the air pressure 
in the outer air and that within 
the middle ear is the opening 
into the throat provided by 
the Eustachian tube. This serves to keep the pressure of 
the air in the middle ear approximately equal to that in 
the outside world. The act of swallowing opens the tube 
and permits the interchange of air. 

The Cochlea. — The inner ear, or labyrinth, is filled with 
lymph. It has two openings into the middle ear, both closed 
by dehcate membranes. One we have mentioned as receiv- 
ing the foot of the stirrup. The joint is made watertight by 
a membrane. This is the oval window. The other, a Httle 
below the oval window, is closed by a single membrane. 
From its shape it is called the round window. We may dis- 



FiG. 5s. — To illustrate the lever 
action of the ear bones, m, the 
hammer; e, the anvil; a, the short 
process of the anvil which abuts 
upon the wall of the middle ear and 
serves as point of rotation; a—b, the 
power arm; a-p, the load arm of 
the lever. 



THE STRUCTURE OF THE EAR 



141 



tinguish two parts of the inner ear, the cochlea and the 
labyrinth proper, — the semicircular canals, utriculus, and 
sacculus. As the cochlea alone is concerned in hearing, a 



msp^ 




Fig. 54. — Longitudinal section of the cochlea of a cat; dc, cochlear duct; gsp, 
spiral ganglion; msp, membrana spirahs (basilar membrane); mv, Reissner's mem- 
brane; n, cochlear nerve; set, scala tympani; scv, scala vestibuli. (From Huber, 
after Sobotta.) 

description of the other structures may be postponed. In 
essentials the cochlea is a tube divided up its middle by a 
partition of bone and membrane. One side of the partition 
is closed by the oval window, the other, or lower, by the 
round window. The tube is wound two and a half times 



142 FUNDAMENTALS OF PSYCHOLOGY 

about a central column of bone, the modiolus. The cochlear 
nerve, the nerve of hearing, enters the centre of the modiolus, 
and ascends to the top, giving off a spiral band of nerves 
from the bottom to the top of the cochlea. It enters through 
the spiral ridge of bone, the lamina spiraHs, and ends in close 
connection with cells tipped with hairs on and about the 
basilar membrane. This basilar membrane, together with 
the lamina spiralis, constitutes the dividing partition of the 
cochlear tube. If one looks at a section of the cochlea, one 
sees five or six sections of the tube (Fig. 54). In each of 
these there are three divisions. The upper one in the figure 
is called the scala vestibuH, the staircase of the vestibule, 
since it connects directly with the vestibule and the oval 
window. A small triangular canal is divided off by the basi- 
lar membrane and a deKcate membrane above it, Reissner's 
membrane. This is the cochlear canal. Below the basilar 
membrane is the scala tympani, which connects with the 
round window. The vibrations of the stirrup are trans- 
mitted to the lymph through the oval window, and ascend 
to the top of the cochlea by the scala vestibuli. At the apex 
is an opening between the scala vestibuli and the scala 
tympani, which is supposed to permit the vibrations to 
pass from one to the other. The delicate membrane of the 
round window permits the Hquid to vibrate as it could not 
were there but one opening to the cavity filled with liquid. 
By virtue of these connections, the Hquid in the cochlea 
vibrates at the rate of the sound wave in the air. 

Sensations of Tone 

The Qualities of Tone. — The problem for the theory 
of hearing is how the vibrations in this Hquid in the cochlea 
may excite the auditory nerve. To answer this question 
we must turn to a consideration of the facts of auditory 



SENSATIONS OF TONE 143 

sensation. The qualities of tone run in a single line from 
low to high. Slow vibrations give low tones, rapid vibra- 
tions high tones. The lowest tones that can be heard vary 
from about twelve to sixteen per second. The upper limit 
was given by Galton at 50,000, by Preyer at 40,000, Bruner 
from 22,000 to 43,000 for different individuals, while Edel- 
mann asserts that some individuals can hear 50,000 vibra- 
tions. Later investigators, working with more accurately 
tuned instruments, which however probably give less in- 
tense tones, obtain values about 20,000 vibrations per 
second. The lower tones are determined by means of large 
forks, the upper usually by a whistle with very short barrel, 
first devised by Galton, of which a new and more accurate 
model has recently been made by Edelmann. The inter- 
mediate tones increase regularly in pitch. 

The accuracy with which the pitch of tones may be dis- 
tinguished varies markedly with the absolute pitch. Tones 
in the middle range can be discriminated much more easily 
than very high tones or very low tones. From 64 to 1024 
V D,i one can distinguish differences as small as 0.3-0.2 of 
a vibration. Above or below this, tones must be much more 
different to be distinguished. At 32 and 2048 V D the addi- 
tion of 0.4 of a vibration can just be noticed, and for very 
high and very low tones, many vibrations may be added 
before a difference is noted. One can distinguish tones 
differing by these amounts and even say which is higher 
and which lower. On the basis of these experiments by 
Preyer, Luft^ and Max Meyer ^ it has been estimated 
that one can distinguish approximately 11,000 different 
pitches. 

^ V D means double or complete vibrations. 

2 Philosophische Studien, 4, 511 ff. 

^ Zeitschr. f. Psychol, u. Phys. d. Sinnesorg. 16, 352 ff. 



144 FUNDAMENTALS OF PSYCHOLOGY 

The Octave. — Within the range of audible tones there 
seem to be critical points similar in a way to the critical 
points in the spectrum.. In the sound series these critical 
points are the octaves of the musical scale. The octave 
corresponds to the spectrum. As one may say that the 
ends of the spectrum are more similar than the middle to 
either end, so double the vibration of any tone gives a note 
that is more similar to it in one respect than the intermediate 
tones. These octaves constitute, for the trained ear at 
least, regularly recurring similar tones. Within the octave 
the notes whose vibration rates form a ratio of 2 .-3, 3 4, 4:5, 
etc. with the lower note of the octave constitute other 
marked resting points or quahties which are recognized at 
once by the musically trained. Trained ears are more likely 
to make a mistake of an octave in the note than to mis- 
take one note for another within the octave. This may 
possibly be due to special training, as many other systems 
of music, the Chinese, for example, seem not to recognize 
the same distinctions, but the balance of evidence at present 
seems to favor the view that the distinction is fundamental. 

Tone-color. — Two other differences in the quahty of 
tones may be mentioned. One, that tones of the same 
pitch from different instruments have a characteristic dif- 
ference ordinarily spoken of as timbre or tone-color, which 
depends upon the overtones that are added to the funda- 
mental. Thus in the C of 64 double vibrations from a 
piano string there are also found the c of 128, the g of 192, 
the c' of 256, the e' of 320, the g' of 384, the seventh over- 
tone of 448 which does not correspond exactly with any note 
in the scale, the c" of 512, etc. Every multiple of the rate 
of vibration of the fundamental is represented, theoretically, 
since they correspond to the nodes in which the sounding 
body vibrates, and these nodes are formed at each small 



SENSATIONS OF TONE 145 

fraction of the length of the surrounding body. The 
first ten overtones can be readily heard when intensi- 
fied by resonators. If one will hold down a key on 
the piano that corresponds to one of the overtones, one 
can hear that overtone continue to vibrate after the funda- 
mental has been dampened by dropping the key. It is 
started into vibration by resonance and continues to vibrate 
for a time after its excitant has stopped. With practice 
one can hear the overtones separately with the unaided ear. 
Each instrument has its own arrangement of overtones, and 
these give it its timbre. The tuning fork has almost none; 
in the piano they are present in fairly even strength, while 
in the violin certain of the high ones are emphasized at the 
expense of the lower. Each of the musical instruments 
owes its pecuHar quaHty to the number, pitch, and relative 
strength of its overtones. 

Vowel Qualities. — The characteristic differences of 
vowels can- be given a similar explanation. Helmholtz and 
Konig believed that they were due to the presence or 
absence of overtones. The overtones were emphasized by 
the resonance of the mouth chamber which is changed in 
shape by the contraction of certain muscles. This supposi- 
tion was confirmed by synthetizing vowels, — for example, 
by putting together simple tones to constitute the funda- 
mental with its overtones. Recently there has been revived 
by Kohler ^ an old theory of Hermann that vowels are not 
dtie to the presence of overtones of the fundamental note 
of the tone, but that the characteristic of the vowel was some 
single note which does not change with the pitch of the 
fundamental, as would be necessary if it were an overtone. 
These characteristic notes were called formants by Her- 
mann and were assumed to be developed by the air blown 
* Kohler, Zeitschrift f. Psychologie, vol. 54, p. 280. 



146 FUNDAMENTALS OF PSYCHOLOGY 

through the mouth cavity, which is given a different form 
for each vowel. Kohler tested a number of individuals by- 
giving them a series of tones which could be gradually 
changed and asking them to say when the tone took 
on a vowel or consonant character. His results indicated 
that the vowels were about an octave apart through 
the scale. In order he gives the following notes as the 
characteristic tones of vowel sounds: m = 130, u = 260, 
= 520, a = 1040, e = 2080, i = 4100, s = 8200, 
f = 17,000, ch = 34,000. All the values are approximate 
only and the sounds are the sounds of the German letters. 
Between the pure vowels are mixed ones. One shades 
gradually over into the other and both elements can be dis- 
tinguished. Dayton C. Miller,^ by an objective method, 
found some of these notes to be present in the vowels but 
not all. He, however, accepts the Helmholtz overtone 
theory of vowels. Not only does this theory serve to ex- 
plain the vowel sounds, but it explains the characteristic 
differences in the series between the octaves. The notes 
repeat themselves in the octaves, and the beginning of the 
repetition is marked by the change from one vowel tone 
to another. It is suggested that the sensations corre- 
sponding to increased vibration rate may be pictured as a 
spiral, with the same notes over each other. 

Beats. — An effect of combinations that is purely sensa- 
tional is found in the beat. If two tones of approximately 
the same pitch are sounded together, there is heard an 
alternate increase and decrease of the tone which comes as 
many times a second as the difference in the number of 
vibrations per second of the component tones. Physically 
this is due to the fact that the component tones will be 
alternately in the same phase and in opposite phases. When 

^ Dayton C. Miller, Science of Musical Sounds, pp. 219-243. 



SENSATIONS OF TONE 147 

they are in the same phase, the resultant will be the sum, 
when in opposite phases, the difference, of the two tenden- 
cies to vibrate. When these alternations come some dis- 
tance apart, they are heard as distinct swelKngs and 
diminutions; when closer together, merely as a roughness 
of the tone. For the theory it is interesting to note that 
most beats seem to be carried by neither of the tones 
themselves, but by a tone intermediate between the 
tones that produce the beats. This we must come back 
to later. 

Tonal Fusion. — Of the various phenomena that were 
mentioned in connection with vision, some are also to be 
noticed in sound. The phenomena of mixture of colors is 
replaced by fusion of tones. The two are not easily com- 
parable, since the result of the combination of tones is 
dependent upon the position of the notes within the octave 
also. Each note in a fusion can with a little practice be 
heard separately; there is no fusion that gives an intermedi- 
ate tone as in color, and no cancellation, no phenomenon 
allied to complementariness. The degree of fusion of the 
whole depends in large measure upon the ratio of vibration 
rates of the two tones; the smaller the numbers that repre- 
sent the ratios, the closer the fusion. The best fusion is fur- 
nished by the octave, whose components give a vibration 
rate of i : 2, the fifth, 2:3, and decreases with the ratios 
represented by larger numbers as the second, 8:9; the 
seventh, 8:15, etc. This relation holds at least approxi- 
mately, although critics have insisted that the degree of 
fusion in certain combinations does not correspond accu- 
rately to the smallness of the numbers that express the ratio 
of vibration rates. Closely related to fusion is consonance 
or the availabihty of the combinations for musical effects. 
This depends partly upon the degree of fusion, more upon 



148 FUNDAMENTALS OF PSYCHOLOGY 

the training of the hearer. This dependence upon training 
is shown by the difference in what is regarded as pleasant 
between occidental and oriental music and in the gradual 
change in the accepted intervals in western music. The 
tritone, the fourth, and the fifth, the only intervals used 
by the Greeks, have gradually given way to the thirds and 
sixths, and now we see seconds and sevenths admitted to 
music under certain circumstances. It is the feeling tone, 
as well as the physical combinations, that determines the 
effect. 

Helmholtz Theory of Consonance. — An explanation of 
consonance is given by Helmholtz on the basis of beats. 
The notes that give the most perfect fusion are themselves 
far enough apart not to beat and, furthermore, do not give 
rise to beats between their overtones. Thus the fifth with 
a ratio of vibrations of 2 : 3 would have as overtones of 
the first components 4, 6, 8, 10, etc., and as overtones of 
the second component 6, 9, 12, etc. Of the first four over- 
tones only the 8 and 9, 9 and 10 would be near enough to 
beat or be dissonant, and two of the first four would be 
identical, the others no less consonant than the fundamen- 
tals themselves. On the other hand, the major seventh, 
with a ratio of 8 115, while giving no beats between the 
fundamentals, would have beats between most of the over- 
tones. The fundamental of the higher, 15, would beat with 
the first overtone of the second, 16, the third overtone of 
the lower beats with the first of the higher, and in general 
there are many beating overtones and no identical ones 
below the eighth of one and the fifteenth of the other. In 
general, then, dissonant chords may have beats either be- 
tween the fundamentals or the overtones, while consonant 
chords have few beats if any between either fundamentals 
or overtones. 



SENSATIONS OF TONE 149 

After-sensations. — Like colors, tones have after-sensa- 
tions, but only positive ones. It requires some time for a 
tone to reach its maximum, and also it persists some little 
time after the physical excitation ceases. The ear is much 
more rapid in its adaptations than the eye, however; it 
has much less inertia. According to Mayer separate tones 
can be heard if they are repeated as frequently as 27 per 
second for notes of 64 V D and 204 times per second for a 
note of 1024. There are also intermittent after-sensations 
of tones, but they are not so often noticed as after-images. 
Urbantschisch reports that single primary after-tones may 
last from one to ten seconds. The intermittent after-images 
may follow each other at irregular intervals for one to two 
minutes. Each after-sensation will last from 10 to 15 
seconds at intervals of from 10 to 20 seconds. Usually 
these intermittent tones are of the same pitch as the objec- 
tive tone, but some may be higher or lower. They are 
fainter than the original and usually fluctuate in intensity. 

Corresponding to color bHndness are rare cases of what 
are called tone islands, — the patients deaf to large portions 
of the scale who can hear notes of intermediate pitch. More 
frequent are individuals whose range of audition is short- 
ened above and below, and it is a fairly general rule that 
the upper notes gradually cease to be heard with increased 
age. 

Combination Tones. — An interesting phenomenon of 
hearing is furnished by combination tones. When two 
notes are sounded, one frequently hears, in addition to the 
notes themselves, tones that correspond to the difference 
between their vibration rates or to the sum of their vibra- 
tion rates. Thus if the tones c and e of 128 and 160 be 
sounded together, one will hear a note corresponding to 
the difference in their vibration rates, 32. One can also 



ISO FUNDAMENTALS OF PSYCHOLOGY 

hear a second difference tone whose rate is the difference 
in rate between the higher and twice the lower (2 1 — h) 
of 96 and a third tone (3 1 — 2 h) of 64. Some authorities 
report that they hear fourth and fifth difference tones named 
on the analogy of the last. The striking aspect of these 
tones is that in part at least they are subjective; they can- 
not be heard more clearly by means of resonators than by 
the unaided ear, and all other means of demonstrating their 
objective existence fail. They must apparently be ac- 
counted for by the physiological or psychological theory 
of hearing. Another combination tone is the summation 
tone. This is a note that corresponds to the sum of the 
vibration rates of the component tones. It is not so easy 
to hear as the difference tones, and it is more difficult to 
obtain pure conditions for it, as in many cases it will corre- 
spond to an overtone or to a difference tone between the 
overtones. The summation tones are probably of subjective 
origin, but no satisfactory explanation has been given of 
how they originate. 

Tone and Noise. — The other even more fundamental 
difference in sounds is that which obtains between tones 
and noise. The difference is sufficiently familiar to need no 
description. Physically as well as psychologically two forms 
of noise are to be distinguished. The more usual is due to 
a very complex mass of tones that have no simple relation 
in their vibration rates, and have even been said to be non- 
pendular in character. Any inharmonious combination of 
many tones is accepted as noise. A noise of this kind passes 
gradually over into tone, as the degree of dissonance is 
lessened, or the tonal element comes to predominate. If 
there are any tones that are not reducible to the ordinary 
pendular or sine form, they may also be present in noise. 
That complex sounds like the sawing of wood or the rattle 



THEORIES OF HEARING 151 

on a city street are merely tones in great number and variety 
without any harmonic relation is probable, since with reso- 
nators one can distinguish tonal elements in them. The 
second t5^e of noise corresponds to a simple vibration too 
short to produce the full tonal character. Upon cutting 
off a pure tone after only one or two full vibrations have 
been made, a sudden noise is heard, which lacks the tonal 
character. This is usually done by passing the tone through 
a tube that can be opened to permit the sound to pass for 
only a fraction of a second. When less than two full vibra- 
tions reach the ear, the effect is a shock. The full tonal 
character of the sound is obtained only when sixteen full 
vibrations are heard. Noise and tone, then, are different 
only in the time of stimulation or in the arrangement or 
combination of the elementary waves, not in the character 
of the waves themselves. 

Theories of Hearing. — The physiological theory can 
be discussed only in connection with the structures about 
the endings of the auditory nerve in the cochlea. As was 
said, the auditory nerve enters the centre of the modiolus 
about which the cochlear canal is wound, and the sheet of 
fibres extends through the lamina spiralis to end in the 
neighborhood of hair cells on the basilar membrane. The 
structures here are somewhat complicated, but the theories 
have made no use of most of the complications. The mem- 
brane that helps to divide the cochlea into two canals con- 
sists in large part of transverse fibres. These for Helmholtz 
constitute the essential part of the basilar membrane. Be- 
low them is a layer of connective tissue which is thicker 
than the layer of fibres. On the basilar membrane are found 
several pecuhar structures. The most striking of these are 
the rods of Corti. These consist of two rows of delicate 
structures curved and fitted together at the top to form a 



152 FUNDAMENTALS OF PSYCHOLOGY 

clearly defined arch. They leave an opening between 
them, the canal of Corti. These rods are not continuous 
longitudinally and are considerably less numerous than the 
fibres of the basilar membrane. On the inner side of the 
arch is one layer of cells with a tuft of hair at the top; on 
the outer side are four or five layers, with similar tufts that 
extend through a membrane, Kolliker's membrane, to the 
lymph of the cochlear canal. Covering the outer portion 
of the basilar membrane are relatively thick epithelial cells. 




Fig. 55. — Organ of Corti. b, basilar membrane; d, outer auditory or hair cells; 
s, inner auditory cell; /, top of outer rod of Corti, forming one side of the arch of 
Corti; o, inner pillar cell; g, tectorial membrane; q, nerve fibres; n, nerve fibres 
extending across the canal of Corti. (From Huber after Retzius.) 

On the inner side, extending out from and well above the 
lamina spiralis, is a delicate membrane, the tectorial mem- 
brane, which hangs free in the Hquid above the entire width 
of the differentiated mechanisms. These can all be made 
out in Figure 55. 

On first sight one would think that the rods of Corti must 
be the essential organ of hearing. They are so highly 
developed and delicate that a teleologist would insist that 
they must have some specific function. 

The most fully developed theory is that of Helmholtz. 
In essentials it assumes that there must be in the ear 
resonators tuned to each tone heard. An analogy can be 



THEORIES OF HEARING 153 

drawn with the piano strings which vibrate in sympathy 
with the tones that are present in the outer air. If one 
speaks in a room with a piano, the tones of the voice will 
be heard sounding after the voice has ceased. If one will 
hold down a key and sing, the corresponding note will be 
distinctly heard to respond in sympathetic vibration. 
Helmholtz beheved that there must be resonators in the ear 
which respond in the same way to the vibration for which 
they are tuned. His first idea was that the arches of Corti 
must be these organs. When they were counted, however, 
it was found that there were only 3000 of them, while it was 
known that some 11,000 tones could be heard. Helmholtz 
then turned for his resonators to the fibres of the basilar 
membrane. These are sufficiently numerous (18,000- 
24,000) to provide a resonator for each tone that can be heard. 
They also show some difference in length, — at the upper 
end of the cochlea they are approximately 0.48 mm. long, 
at the lower end about 0.04. This is not difference enough 
to account for the difference in pitch that they are supposed 
to show, but Helmholtz assumed that they were differently 
loaded and tuned by that means for the different tones. 

In the completed theory, then, it was assumed that in the 
basilar membrane are fibres, or really sections of the mem- 
brane, tuned to each note heard. The various complex vibra- 
tions are impressed upon the liquid of the inner ear by the 
oscillations of the stirrup, and these are analyzed into their 
parts by the fibres. In a piano tone, or other note rich in 
overtones, a separate fibre is set into vibration by the 
fundamental and by each of the overtones; in a chord each 
component similarly arouses a different fibre or group of 
fibres and each is sent to the centres by a separate nerve. 
The vibrations of these fibres serve in some way not made 
very clear to stimulate the nerve fibres between the hair 



154 FUNDAMENTALS OF PSYCHOLOGY 

cells. The vibration of the fibres is dampened by the tec- 
torial membrane, which is assumed to drop down upon 
them when the sound ceases. Noises were at first assigned 
to the vestibular structures, but when these were discovered 
to have another function, they too were regarded as due to 
excitations of many fibres in the basilar membrane. In- 
direct evidence was found to support the theory in the fact 
that in cases of deafness to part of the scale, parts of the 
basilar membrane were likely to be diseased. Von Bezold 
has found that patients who have the so-called tone islands, 
parts of the scale that they can hear, while deaf to most 
notes, also are found after death to have lesions in the cor- 
responding part of the basilar membrane. In the aged the 
lower part of the basilar membrane is often in a pathological 
condition, and they fail to hear high tones. 

Details of Helmholtz's Theory. — The theory is adapted 
to explain a number of the facts of hearing. Beats may 
be regarded as due to an overlapping of the vibrating 
portions of the membrane, and thus as giving rise to an in- 
terference phenomenon in the intermediate fibres. On this 
assumption each tone would cause a ribbon of several fibres 
to vibrate instead of a single fibre as Helmholtz first as- 
serted. When they were near together, the outer edges 
of the two ribbons would have common fibres. These would 
tend to vibrate with the rates of both notes, and the inter- 
ference of the two movements would cause the beats. This 
view receives support from the fact mentioned earlier that 
it is a note intermediate between the other two that beats 
rather than either of the component tones. It is the 
intermediate fibres that are vibrating at two different rates 
and consequently carry the beats. When the vibrating 
ribbons are sufficiently far apart there are no interferences 
and so no beats. 



THEORIES OF HEARING 155 

The explanation of difference tones is not so satisfactory. 
Helmholtz at first thought they might be beat tones, misled 
by the fact that there would be as many beats per second 
as the vibrations per second of the difference tones. This 
was given up when it was seen that the beats could not stim- 
ulate the corresponding fibre in the basilar membrane. His 
final explanation was that they must be produced in the 
middle ear. He demonstrated by a differential equation 
that a membrane loaded on one side alone when excited 
simultaneously by two rates of vibration should produce a 
third vibration that corresponds in its rate to the difference 
between the rates of the two components, but he did not 
point out the physical correlates of his mathematical 
values. 

On the whole the Helmholtz theory is the most detailed; 
it accounts for more facts than the others and receives more 
incidental support. Its weakness is a confhct with the 
anatomical findings. The basilar membrane does not con- 
sist of a series of delicate fibres hanging relatively free and 
separated from each other. Instead, the fibres are em- 
bedded in a mass of tissue on both sides thicker than the 
fibres themselves. Ayres tested the possibihty of the 
basilar membrane's vibrating to tones on the ear of a crimi- 
nal who had just been executed, and found that even with 
this perfectly fresh material and the most favorable condi- 
tions no vibration in the basilar membrane could b2 
detected. 

Telephone Theories. — Other theories abandon the 
resonator principle, assuming instead that some structure 
in the cochlea must vibrate as a whole and the analysis of 
the separate tones be made by the cortical centres. Hensen 
and Rutherford have assumed that the basilar membrane, 
acting much Hke the plate of a telephone, transmits the 



156 FUNDAMENTALS OF PSYCHOLOGY 

complex notes to the cortex where analysis takes place. 
Max Meyer has a somewhat similar theory. His assump- 
tion is that the intensity of the tone is determined by the 
distance the vibration extends inward from the oval win- 
dow, while the quahty is determined by the rate of vibration 
of the membrane as a whole. Hardesty^ has abandoned the 
basilar membrane as the vibrating mechanism and assumes 
that the tectorial membrane is the receiving organ. Har- 
desty argues that the vibrations of the Hquid are taken up 
by the tectorial membrane and communicated to the hair 
cells and thence carried to the brain, where, as in the other 
theories of this type, analysis takes place. The difficulty 
with this whole group of theories lies in the assumption that 
differences in vibration rate so sHght as one in ten thousand 
should be appreciated by the cortex, while the most delicate 
appreciation of differences in intensities is one in a hundred. 
The difference in intensity that can be appreciated by the 
ear is only one in five. On teleological grounds, which of 
course have Httle weight, it seems inexplicable that the 
extension of the auditory nerve over such a wide area with 
relatively complicated end organs should have no particular 
function. 

It can be seen that in spite of the ingenuity and assiduity 
of investigators and theorists, a satisfactory theory of 
hearing is yet to be developed. The Helmholtz theory has 
the advantage of all the others in the number of facts that 
it explains and the detailed nature of its explanation; it 
suffers from the improbability of its demand that the 
fibres of the basilar membrane vibrate separately. On the 
other hand, the theories that give a plausible explanation 
of the way the anatomical structures may act make large 

1 Hardesty: On the Nature of the Tectorial Membrane, etc. American 
Journal of Anatomy, Vol. VIII, p. 109. 



CUTANEOUS SENSATIONS 157 

demands on our ability to distinguish differences between 
vibration rates. 



REFERENCES 

Watt: The Psychology of Sound. 

Ladd-Wood WORTH : Elements of Physiological Psychology, 

pp. 196-208. 
Myers: Experimental Psychology, Chs. III-IV. 
Howell: Physiology, Ch. XX. 

Helmholtz: Sensation of Tone. Tr. Ellis, 2d edition. 
Schaefer: Der Gehorsinn, Nagel's Handbuch der Physiologic, 

Vol. Ill, pp. 476-588. 

Tactual Sensations 

Cutaneous Sensations. — The sensations from the skin 
are simplest of all, and their organs are most accessible, 
but only in the present generation have the more important 
facts concerning them been discovered. The same dis- 
tinctions between physical stimulus, physiological processes, 
and sensations, that we have been compelled to make in the 
other senses are to be drawn here. The adequate stimuli 
for the skin are mechanical and thermal. But while the 
stimuli vary only in intensity, different sense organs are 
affected by different intensities, and corresponding differ- 
ences in sensation result. This is most marked in the tem- 
perature sense. The physicist assures us that cold is nothing 
positive, but merely a reduction in the amount of heat. 
Nevertheless when the temperature is reduced below about 
30° C. a sense organ is excited which gives rise to the sensa- 
tion of cold, and this sensation increases as the tempera- 
ture is lowered. Above 30° another organ is stimulated and 
its activity increases as the temperature rises. Similarly, 
slight mechanical stimuli excite sensations of pressure; 



158 FUNDAMENTALS OF PSYCHOLOGY 

and intense ones, sensations of pain. We then have fouf 
distinct sense quahties, while there are but two kinds of 
physical stimulus. More clearly than in any other organ 
can the sense qualities be shown to depend upon the organ 
stimulated. 

Temperature 

The discovery of the distribution of the organs, and with 
that the settlement of most of the problems of cutaneous 
sensibility, is a matter of comparatively recent date. It 
came first in the temperature senses. At approximately 
the same time and altogether independently of each other 
three investigators, Blix, a Scandinavian (1882), Gold- 
scheider, a German, and Donaldson, an American (both 
1885), found that the skin was sensitive to temperature 
only in relatively isolated spots rather than all over, as had 
been earher supposed. The skin was carefully tested point 
by point with a cooled or heated metal point, and it was 
found that at certain points irregularly arranged one would 
feel cold, at others, warmth. The most important disagree- 
ment in the results found was between Goldscheider on the 
one side and BHx, with practically all later workers, on the 
other. Goldscheider found warm and cold points to be 
thickly scattered everywhere on the skin; for example, on 
the back of the hand there were 68 cold spots and 56 warm 
spots on a square centimetre. Blix reported that they were 
much farther apart, and all later investigators have con- 
firmed his results. Sommer counted carefully the number 
in many square centimetres and found that there were from 
6 to 24 cold spots, and from o to 3 warm spots, to the square 
centimetre. He gave as his average 12 to 13 cold and i to 
2 warm spots. His estimate for the whole body was 250,000 
cold and 30,000 warm spots. 



CUTANEOUS SENSATIONS 



159 



Indirect Evidence of the Existence of Warm and Cold 
Spots. — Many of the earlier theories assumed that there 
must be a single organ for warmth and cold. Hering, for 
example, had a theory which would make warm and cold 
depend upon assimilation and dissimilation in the single 



+••• 



/• + . 
■f ^* 



+ + 

.+ + + 



++ 
+ 






• + 



» +• 

+ 
• + +4. 



Fig. 56. — Map of temperature spots on volar surface of the forearm. The dots 
represent warm spots as tested at a temperature of 41-48° C; the crosses, cold 
spots tested at 10°. (From Howell after von Frey.) 

organ, in very much the same way that his complementary 
colors depended upon those processes in the single color 
organ. It was therefore essential when the spots were first 
mapped to prove by other evidence that the spots were 
distinct. Certain characteristic differences in the way the 
two organs respond and in the substances that stimulate 
them provided this evidence, i. It takes considerably 



i6o FUNDAMENTALS OF PSYCHOLOGY 

longer to stimulate the warm spots than the cold spots, per- 
haps an evidence that the former are farther from the sur- 
face. 2. Certain inadequate stimuU will affect one but not 
the other. Cold is particularly easy to excite by induction 
currents, by pressure, or even by heat. Menthol stimulates 
the cold, carbon dioxide the warm organs. 3. There are 
certain larger areas of the body in which only one sort of 
sensation will be found'. Thus on the cornea and con- 
junctiva of the eye cold alone is felt, warmth is lacking 
altogether. That there are different organs for cold and 
for warmth is not now disputed. 

The Temperature Scale. — The more detailed relation 
between the physical temperature and the sensations that 
result from the stimulation may be given. The critical 
point for most purposes is the so-called physiological zero 
point that separates cold from warm. This point varies 
much with the temperature to which the skin has been 
adapted. For a covered part of the body, it is apparently 
in the neighborhood of from 28° to 30° C; on the back of 
the hand, it has been found to vary between 23° and ^$°, 
and after the hand has been immersed in water at 11° for 
some time, water at 1 2° seems warm, and it may similarly 
be adapted for temperatures of 39°. The width of the in- 
difference point seldom is greater than 0.5°. If we assume 
an indifference point at 30° C, below it the cold spots alone 
are stimulated to somewhere in the neighborhood of 10°, 
where pain is added to the complex. Above, one obtains 
warmth alone up to 45°. Here the cold spots are excited in 
addition to the warmth, and the combination gives hot as 
opposed to lukewarm. This excitation of the cold organ 
by a hot stimulus gives what is known as a paradoxical cold. 
The fact was first discovered by Alrutz and has been con- 
firmed by von Frey. One experiment performed by Alrutz 



CUTANEOUS SENSATIONS 



i6i 



was to fatigue the warm spots in the foot by keeping it 
immersed for some time in warm water and then to swing 
it quickly through hot water. The hot water then seemed 
cold. Above 50° to 55° the sensation of burning heat makes 
its appearance as a consequence of the mixture of pain with 




Fig. 57. — Temperature scale. Shows the sense organs stimulated and the 
degree of stimulation at different temperatures. Figures on the base line indicate 
the temperature in centigrade, the height, the degree of stimulation. (After von 
Frey.) 

the other sensations. The question naturally arose as to 
whether there was a paradoxical warmth at the lower ranges 
similar to the paradoxical cold. The burning sensation 
after long exposure to cold suggests that the warm spots 
might be stimulated. Experiments by Alrutz and Thun- 
berg, however, gave no warrant for the assumption. The 
warm or hot sensations at low temperatures are probably 
due to the mixture of sensations of pain with some tinglings 



i62 FUNDAMENTALS OF PSYCHOLOGY 

due to changes in circulation. Figure 57 shows these various 
phenomena in diagrammatic form. 

Pressure and Pain 

Mechanical Cutaneous Sensations. — Very much the 
same distinction may be made between pressure and pain 
as between warmth and cold. Goldscheider also discovered 
that only certain points on the body would respond to pres- 
sure. There was approximately the same difference of 
opinion between Goldscheider and the others as to the 
number of spots. Goldscheider found many, the others 
relatively few. Von Frey, who has done the most careful 
and most recent work on the pressure sensations, found that 
there are from o to t^oo per square centimetre. On the whole 
body surface, excluding the head, where they are the most 
numerous, he estimates there are approximately 500,000. 
They are more numerous than either kind of temperature 
spots. In determining their position von Frey used fine 
hairs mounted on matches or similar small bits of wood. 
These gave a very small point and a constant pressure. 
Wherever there were hairs on the body he found that the 
pressure spots correspond to them. They are also found on 
the surfaces free from hairs. 

Sensations of Pain. — Pain has been even more in dispute 
than the other senses. Until von Frey's^ work in 1896 it 
had usually been held either that pain was a feeling, not a 
sensation at all, or, if it was a sensation, that it must be 
regarded as due merely to the overstimulation of the pres- 
sure organ. Goldscheider in his investigations modified 
this view slightly. Pain stimuli were carried to the spinal 
cord by the same neurons as pressure, but there took a dif- 
ferent course. While the pressure sensation continued by 

^ Leipziger Abhandlung, 1896 



CUTANEOUS SENSATIONS 163 

the same neurone up the posterior columns, the intense 
impressions were supposed to force a way across a synapse 
to new neurones with cells in the central gray and take 
another path. As evidence that there is this more difficult 
path through the central gray, Goldscheider adduces the 
long time required to receive pain sensations. The reaction 
time for pressure is from 0.12 to 0.2, while the time for pain 
rises to 0.6 to 0.8 second. He uses this theory also to explain 
summation pains such as those involved in the Chinese 
water torture, in which drops of water are permitted to fall 
for a long time upon the same point until the successive 
sHght stimuli give rise to an unbearable pain. The summa- 
tion is assumed to take place in the cells of the cord. Also 
the effects in the disease syringomyelia are mentioned as 
confirmatory of his theory. In this disease an infection 
extends from the central canal, destroying the cells in the 
surrounding gray matter. Patients suffering from this 
disease feel only pressure and cold in certain areas of the 
skin, but have no sensations of pain and warmth. Gold- 
scheider interpreted this to mean that the paths for pain 
were destroyed, while the paths through the white matter 
were left intact. Goldscheider, too, explained on this 
theory the 'referred pains' so prominent in most diseases. 
He assumes that two or more regions of the body are con- 
nected with the same cells in the cord. Thus he would say 
that the mucous membrane of the stomach and the skin 
of the back were connected with the same cells in the cord. 
When certain disturbances of the stomach developed, the 
excitation of its nerves would be carried to the cells in the 
cord that give rise to the sensation of pain, and the sensa- 
tion would be excited in the cortex. But since the same cells 
also transmit pain impulses from the middle of the back, 
and we are much more familiar with that area, the pain 



i64 FUNDAMENTALS OF PSYCHOLOGY 

would be referred to the known region, the back, rather 
than to the wall of the stomach, a surface never 
seen and where voluntary contact has never produced 
pains. A somewhat similar theory of referred pains has 
been given by Head^ without accepting the other portions 
of Goldscheider's theory. 

Pain Spots. — More recent investigations have shown 
that the first part of Goldscheider's theory, that pain and 
pressure impulses have the same path to the cord, is probably 
incorrect. Von Frey, in particular, by very careful mapping 
of the skin, has shown that there are special pain spots in the 
skin in addition to the pressure and temperature spots. The 
mapping was on an enlarged scale diagram of the small 
portion of the skin worked with. The skin was explored 
with a sharpened horse hair under a magnif3dng glass, and 
it was found that sensations of pain were given only at cer- 
tain points, mostly in the small lines of depression on the 
skin. These were found to be much less sensitive than the 
pressure spots, required about one thousand times as great 
a pressure to stimulate them, and were much more numer- 
ous than any other, on the average, one hundred to the 
square centimetre. It was estimated that there are between 
two and four million pain spots on the surface of the body. 
Much corroboratory evidence has been brought to confirm 
the results of mapping the spots. It has been found that 
there are some parts of the body, the conjunctiva of the 
eye, for example, where there are pain spots but no pressure 
spots; others, as the inner lining of the cheek, where there 
are pressure spots but no pain spots. Another bit of evi- 
dence depends upon the slow response to pain mentioned 
above. If a pressure spot be stimulated by a slight alter- 
nating electric current with alternations of fifty or sixty 

1 Brain, 1893. 



CUTANEOUS SENSATIONS 



165 




Fig. 58. — Termination of 
sensory nerve-fibres in the 
mucosa and epithelium of 
the cat. (From Huber.) 



FUNDAMENTALS OF PSYCHOLOGY 



per second, the separate alternations will be noticed. If, 
on the contrary, the current be appKed to a pain spot, 
there is a continuous sharp sensation. 

\ 




Fig. sg. — Nerve endings in skin and about hair follicles, c, superficial plexus of 
fibres in skin (free nerve endings are still nearer the surface), h, the hair with 
nerves about root (From Barker, after Retzius.) 

Cutaneous Sense Organs. — The sense organs for these 
different sensations have been determined with varying 



CUTANEOUS SENSATIONS 



167 




Fig. 60. — Tactile cor- 
puscle of Meissner from the 
skin of the toe. N, nerve 
fibre. (From Barker.) 



degrees of certainty. Pressure spots seem closely connected 
with the hairs on the parts of the body where there are hairs. 
The spot that responds is always just 
over the root of a hair (Fig. 59). It 
is probable that the nerve about the 
root is stimulated by the hair which, 
as it is bent, acts as a lever. On the 
surfaces without hairs, the palms 
and soles of the feet, von Frey sug- 
gests that the Meissner corpuscle 
(Fig. 60) is the organ. Pain spots 
are ascribed to the free nerve endings 
(Fig. 58). These come closest to the 
surface of any of the end organs in 
the skin and the sensations of pain 
are aroused by the most superficial 
stimulations. Acids that affect only 
the epidermis give pain sensations without sensations of 
pressure or temperature. It is more difficult to determine 
the organs for temperature and the results are less trust- 
worthy. Following 
von Frey again, we 
may regard the end 
organs of Krause 
(Fig. 61) as the sense 
organs of cold, since 
they with the free 
nerve endings are the 
only sense organs found in the conjunctiva, where also 
only pain and cold can be felt. Because the sensations of 
warmth seem to originate well below the surface and the 
organ of Rufi&ni also is found relatively deep, that has been 
regarded as the sense organ of warmth (Fig. 62). 




Fig. 61. — End bulb of Krause. (From Barker.) 



i68 FUNDAMENTALS OF PSYCHOLOGY 



Regeneration of Cutaneous Sensations. — An experi- 
ment performed by Head and Rivers tends to establish a 

second classification of cutaneous 
sensations that has not been 
brought into complete agree- 
ment with the one given above. 
They cut the ulnar nerve where 
it is near the surface at the elbow 
and then studied the sensations 
that remained and the gradual 
reappearance of sensations as the 
nerve regenerated. At once, 
after the nerve was cut, all sen- 
sations from the skin proper dis- 
appeared. Neither pressure nor 
pain, warmth nor cold, could be 
felt. When more intense stimu- 
lation was applied, pressure and 
pain could be felt from the 
tissues under the skin, of ap- 
proximately the same quahty as 
from the normal deeper tissue 
in the arm. This they call the 
deeper lying sensibility. After 
the lapse of forty-three days, 
sensations first began to return 
to the skin. The first evidence 
of regaining sensation was in 
the diminution of the area in- 
sensitive to pain. On the one 
hundred twelfth day sensations of cold made their appear- 
ance, and the area sensitive to pain had much increased. 
Nearly two months later the hairs were found to be sensi- 




FlG. 62. 



— End organ of Ruffini. 
(From Barker.) 



CUTANEOUS SENSATIONS 169 

tive to light touch and a few warm spots made their appear- 
ance. One hundred and ninety days after the operation all 
of the sense qualities had returned over approximately the 
entire area. But each of the sensations was limited in some 
way as compared with the normal. Temperatures below 
37° C. and above 27° C. could not be felt at all. Pain sensa- 
tions could be felt only from unusually intense excitations, 
and then were exceedingly disagreeable and diffuse, and 
were generally referred to some point at a distance from the 
one stimulated. Touch could be felt only on the hairs, — 
when an area was shaved, no touch was felt. The sensibiHty 
producing this condition the investigators call protopathic. 

Curiously enough one small triangle in the affected region 
was discovered in which all the qualities were present that 
were lacking from the rest. Temperatures between 27° 
and 37° C. could be noticed, but none of the extremes. No 
pain was felt; pricks gave mere sensations of contact and 
were always correctly localized. Perhaps most remarkable 
of all, light contact with cotton wool was appreciated on 
this small triangle from the beginning and was correctly 
localized whether hairs were or were not stimulated. This 
more highly developed and more accurate sensibility was 
known as the epicritic. After the lapse of a year, the epi- 
critic sense returned to the entire area. The protopathic 
sensibility had reappeared in the small triangle with epi- 
critic sensitivity only, one hundred ninety-eight days after 
the operation. This experiment indicates that three sets 
of sensory nerves supply any member. One is found in the 
deep tissues, the two others in the skin. Of the latter one 
provides the coarser, more intense sensations, the other the 
more delicate. The protopathic is stimulated only by rela- 
tively intense pressure and that only on the hairs; very 
intense stimuli also give pain. It also is affected by the 



lyo FUNDAMENTALS OF PSYCHOLOGY 

extremes of temperature alone. The epicritic sense, on the 
other hand, supplies the gaps left by this sense; it appre- 
ciates moderate temperatures and slight pressures. The 
relation between the separate spots that have been shown 
to produce the specific sensations and the epicritic and 
protopathic sensibilities has not been completely worked 
out. It seems difficult at first sight to harmonize the two 
sets of results, and another series of observations on a sub- 
ject with a regenerating nerve which shall include mapping 
of the spots at different stages is desirable to complete our 
knowledge, and to determine how far the two can be made 
to agree. ^ Later workers, Trotter and Davies,^ and Boring,^ 
have not confirmed these results altogether. They found a 
gradual return of each sense, — pain, pressure, and cold 
returning together, and warmth considerably later. 

Sensations of Taste 

Gustatory Sensations. — While tactual sensations have 
been found much more numerous than was thought as 
knowledge about them increases, sensations of taste have 
been diminished in number quite as definitely and markedly. 
The popular mind to-day and the scientific opinion of one 
hundred years ago assumes that there are a very large 
number of taste qualities. Even after experiments had 
been made, it was generally believed that at least six could 
be distinguished. The older list included nauseating tastes, 
aromatic, and other qualities that we now know to be 
derived from smell. Chevreul showed in 1824 that these 

1 Rivers and Head, A Human Experiment in Nerve Division, Brain, 
xxxi, 323. 

^ Trotter and Davies, Experimental Studies in the Innervation of the 
Skin. Journal of Physiology, Vol. XXXVni, 1909, pp. 109, 134 ff. 

3 Boring, Cutaneous Sensation after Nerve Division. Quarterly Journal 
of Experimental Physiology, Vol. X, pp. 1-96. 



SENSATIONS OF TASTE 



171 



must be smell qualities by his discovery that they disap- 
peared upon closing the nostrils. Until relatively recently 
salt, sweet, sour, bitter, metallic, and alkaline were regarded 
as the primary tastes. The metallic seems on closer experi- 
mentation to be a compound of taste with smell and with 
mechanical and perhaps muscular sensations. The metallic 
surface may produce slight muscular contractions in the 




Fig. 63. — Fungiform papilla from human tongue. (From Huber.) 

neighborhood of contact which add to the other taste and 
smell sensations to produce a complex. Alkalies if strong 
may make the tongue slippery and may also produce 
puckering of the surface of the tongue. Von Frey has shown 
by closing the nostrils while tasting that alkalies also contain 
odors. When the tongue is at rest and the nose closed, the 
only sensation is a slight bitterness. Eliminating all sensa- 
tions of smell, which furnish a large part of what is called 
taste in' gastronomic relations, and all tactual and tempera- 



172 FUNDAMENTALS OF PSYCHOLOGY 

ture sensations, such as the biting of spices, etc., we have 
left only four true tastes, — sweet, salt, sour, and bitter. 

Sense Organs of Taste. — The problem of the organ of 
taste, and its specific type of reaction, is similar to the same 
problem on the skin, but sHghtly more complicated. The 




Subgemmal Cell 




Intergemmal Fibrils 

Fig. 64. — Taste buds and endings of gustatory nerve; a shows taste cells about 
a central supporting cell; b, fibrils around and between the taste buds. (From 
Barker.) 

sense endings of taste are found primarily upon the tongue, 
but also in some numbers upon the soft palate, upon the 
cords of the larynx, the epiglottis, and in children on 
the inner lining of the cheek. On the tongue the end-organs 
are the papillae. These are elevations set deep in the mu- 
cosa. The sense ends are on the sides of the resulting folds. 
The most striking are the circumvallate papillae, from seven 



SENSATIONS OF TASTE 173 

to twelve circular depressions, much like the moat of a 
walled town, arranged in an angle upon the back of the 
tongue. The most numerous type in man are the fungiform, 
whose small red openings may be seen upon the tip of the 
tongue. In some human beings the foliate papillae are 
present and have sense organs. They are very prominent 
in animals. The real sense ending is the taste hud or beaker. 
These are collections of taste cells and supporting cells 
arranged in the form of a bud. The taste cells have hairs 
on their ends that extend into the papillae where they come 
into contact with the saliva in which the chemical substance 
that gives rise to the taste has been dissolved. Around 
the taste cells are nerve iibrils bare of their medullary 
sheaths. The function of the papillse is apparently to 
catch the saliva and permit it to come into contact with the 
taste cells, and there to start the nervous impulse. 

Doctrine of Specific Energies for Taste. — Much discus- 
sion has been devoted to the question whether a single 
taste bud in a papilla can give rise to one only or to more 
than one sensation. Experiments performed by Oehrwall of 
stimulating the papillae separately showed that more than 
one sensation might be received through a single papilla. 
He mapped accurately 125 papillae and then stimulated 
each separately with solutions of sugar, quinine, and tar- 
taric acid. Of these, 27 gave no response at all, 60 responded 
to all three substances, 12 gave acid only, 3 sweet only, none 
bitter only, 4 gave sweet and bitter, 12 sweet and acid, 7 
acid and bitter. From this experiment, which has been 
repeated by several investigators with approximately the 
same result, it is evident that the papillae cannot be re- 
garded as the organs of different special sense qualities as 
are the spots on the skin. It is suggested by the supporters 
of the doctrine of specific energies that the immediate sense 



174 FUNDAMENTALS OF PSYCHOLOGY 

end is the taste bud and that, as there are always many of 
these in each papilla, it is possible that each taste corre- 
sponds to a particular sort of nerve end, but that several 
different kinds are found in each papilla. As the separate 
beakers cannot be stimulated individually, this assumption 
cannot be confirmed directly. Some indirect evidence in 
its favor is offered by the fact that on the application of 
certain drugs the tastes disappear one at a time, presumably 
due to the fact that the primary end organs are affected 
with different ease. Thus, cocaine applied to the tongue 
destroys first the sensation of bitter, and the others in suc- 
cession, while gymnemic acid first destroys the sensation 
sweet. Similarly, the distribution of the taste sensitivity 
on the tongue tends to confirm the same theory. Bitter is 
most prominent on the back of the tongue, — in some indi- 
viduals is confined to that region ; sweet is more pronounced 
on the tip, sour on the sides, while salt is more generally dis- 
tributed. The distribution varies from individual to indi- 
vidual. In some, bitter will be lacking altogether on the 
tip, while in others it is present, but in few papillae. A 
similar statement may be made for each of the taste quali- 
ties. As further evidence that there are specific endings 
for each quality, the same substance will produce a different 
taste as it is applied to one part of the tongue or the other: 
sodium sulphate has a sweet taste on the tip, a bitter taste 
on the back of the tongue, a difference that must be due 
to the organ stimulated. Similarly, pressure or electrical 
stimulation of the chorda tympani, one of the nerves of 
taste, where it passes through the middle ear, may produce 
sensations of taste. Still another bit of evidence for the 
independence of the organs for the different tastes is differ- 
ence in the time required for stimulation. On the tip of 
the tongue salt requires from 0.25-0.72 second to be appre- 



SENSATIONS OF TASTE 175 

dated, sweet, 0.30-0.85, sour, 0.64-0.70, bitter, 1-2 seconds. 
The longer time for bitter is especially striking. While the 
doctrine of specific energies is not open to direct test, the 
indirect evidence, so far as it exists, supports the h3^oth- 
esis. 

Attempts have been made to discover some relation be- 
tween the chemical composition of substances and their 
tastes. As is well known, acids are sour so generally that 
the two words are popularly synonymous as apphed to 
taste, and in German are designated by the same word. 
There are, however, many exceptions on both sides. For 
the other qualities the lack of relation between the chemical 
composition and taste is striking. The more familiar sweets 
are carbohydrates, but lead acetate, salts of the other heavy 
metals, and even some alkalies have sweet as one of the 
component tastes. Much the same statement may be made 
of the bitter substances. Usually they have a complex 
molecule, and the more complex, the more bitter, but no 
more accurate law has been developed. The simple salts 
are usually more or less salt, but there are many exceptions. 
In general, the attempts to correlate taste and chemical 
composition have led to no noteworthy results. 

Taste Fusions and Taste Contrasts. — The taste qualities 
show some of the interrelations found in vision. Tastes mix 
with each other, with the cutaneous sensitivities, and with 
odors to produce complexes that are not readily analyzable. 
The statements hold less for taste alone than for mixtures 
with the cutaneous and olfactory senses. It seems that 
sweet and sour, sweet and bitter, combine in foods to advan- 
tage. Salt and sweet have approximately the relation of 
complementary colors. When mixed in weak solutions, 
Kiesow found that they nullify each other. Also when 
apphed to neighboring areas of the tongue, they reenforce 



176 FUNDAMENTALS OF PSYCHOLOGY 

each other, that is, show contrast effects. Thus if one 
pour upon one side of the tongue a solution of sugar too 
weak to be tasted alone, and upon the other a salt solution, 
the sweet will be noticed. Even distilled water may by 
the same means be given a sweet taste. Other tastes, 
as sweet and bitter, applied to opposite sides of the 
tongue, when intense, may alternate; first one appears, 
then the other, a process resembling binocular rivalry of 
colors. 

The nerves of taste offer some complication. According 
to Zander, there are three nerves of taste and one of cuta- 
neous sensibility. Of the true taste nerves, the glosso- 
pharyngeal, the ninth, supplies the back portion of the 
tongue ; the vagus supplies the taste buds of the larynx and 
epiglottis and a small area on the very back of the tongue; 
while the chorda tympani carries the sensations from the 
forward areas. The chorda tympani enters the tongue as a 
part of the lingualis, the other portion of which is a branch 
of the trigeminus, and is the nerve of cutaneous sensibility. 
In its midcourse it is alone, and then enters the brain stem 
as part of the intermediate nerve. 

Sensations of Smell 

Olfactory Sensations. — The organ for smell is situated 
in a narrow cleft at the very top of the nasal cavity, just 
under the olfactory lobe at the base of the brain. The 
olfactory area is marked by a brown pigment which extends 
over the upper portion of the septum and the roof of the 
olfactory fissure. The olfactory area is much smaller in 
man than in animals that make more use of the olfactory 
sense. The olfactory fissure is above the direct respiratory 
path — only eddies of the air inspired or expired reach it. 
This is a protective measure, as dust and other harmful 



SENSATIONS OF SMELL 



177 



impurities are largely prevented from affecting the endings. 
The end organ proper is found in the olfactory cells, true nerve- 
cells, which here alone reach the outer surface of the body 
(Fig. 65) . These cells end in hairs that project slightly from 
the surface. The axones of the cells pass upwards through 
numerous openings in the skull to make connections in the 




Fig. 65. — Olfactory apparatus. D, the olfactory membrane and endings; B, 
glomeruli where end-brush of olfactory neurones connects with dendrite of the 
more central neurones. (From Barker, after Ramon y Cajal.) 



glomeruli with neurones of the olfactory lobe, and thence 
to connect with the cortical areas for smell. Between the 
olfactory cells are supporting cells. The chemical substance 
that gives rise to the odor is carried in the inspired or expired 
air and comes into direct contact with the hairs of the ol- 
factory cells, where we may assume that the chemical reac- 
tion excites the nervous impulse. 



178 FUNDAMENTALS OF PSYCHOLOGY 

Olfactory Qualities. — How many sensations of smell 
there are is still a moot question. The organ is so situated 
that no direct experiment may be made upon it, and the 
indirect experiments either have not been carried far 
enough or are inaccurate. Aronsohn long ago attempted to 
determine the number by a fatigue method. His theory 
assumed that one might tire the organ by smelling some one 
substance, rosewater, for example, until that substance 
could no longer be detected, and then while the fatigue per- 
sisted, test the odors of different substances. Any that 
could still be detected would belong to some other class, 
must be sensed through some other organ; those that could 
not be distinguished would belong to the same class. The 
method has been proved to be practical, but the large 
number of substances to be tested and the difficulty in 
knowing whether the organ is still fatigued for the standard 
odor have prevented its extensive application. Other evi- 
dence of the existence of separate olfactory organs is fur- 
nished by pathology. In some diseases of the olfactory 
region, appreciation of certain odors will be lost while 
others will still be noticed. But the observations have not 
been carried far enough to give an accurate classification. 

Henningi has recently made a classification of odors by 
questioning men who had special skill in discriminating 
them. His conclusion is that we may distinguish six 
primary quahties with a series between each that partakes 
of the quahties of the two extremes. These fundamental 
odors are the spice odors, flower odors, fruit odors, resinous 
or balsam odors, foul odors, and burning odors. Instances 
of the first class are fennel, cloves, sassafras oil. Included 
in the flower or fragrant odors are hehotrope, oil of jasmin, 

1 H. Henning, Der Geruch. Zeitschrift f. Psychologic, vol. 73, p. 161; 
vol. 74, pp. 203, 305. 



SENSATIONS OF SMELL 179 

and oil of geranium. The fruit odors include the fruits 
proper, oil of citronella and ethyl ether. The resinous or 
balsam combinations include turpentine, oil of eucalyptus 
and oil of cedar, as well as the true resins. The foul odors 
are typified by hydrogen sulphide and other sulphur com- 
pounds in addition to bad cheese and similar disagreeable 
odors of organic origin. The burning odors are typified by 
smoke, minus the burning sensation, pyridin, and tar. 

Henning arranges these odors on a prism with the primary 
odors at the corners and the intermediate ones on the lines 
joining them. Typical intermediates between fruit and 
foul are dill, leek, celery, onion, oil of mustard, and foul 
cheese; between the burning and spicy Hes browning coffee; 
between burning and resinous, burning varnish. The pri- 
mary odors of Henning correspond very closely with many 
of the older classifications. The principal difference is that 
he omits a number included by the older men which are 
compounds of smell with pain and other senses. His 
results can be readily tested and on the whole confirmed. 

These quahties mix with the cutaneous sensations from 
the mucous membranes of the nose, — one quality of smoke, 
for example, is the same from the eyes as from the nose, — 
and with tastes. We usually do not distinguish the different 
components: if the complex comes from food in the mouth, 
we call the whole a taste; if from the air outside, we call 
the whole an odor. 

Attempts have been made to connect the quahties of 
smell with the chemical composition of substances. In 
general it may be said that most odorous substances are 
found in the fifth, sixth, and seventh groups in the system 
of Mendeleeff. Haycraft has also shown that in many 
cases the intensity of the smell in a group increases fairly 
regularly with the complexity of the molecule. There are 



i8o FUNDAMENTALS OF PSYCHOLOGY 



exceptions to these rules and no complete formulation may 
be made of them. It is probable that the chemical substance 
is borne on the inhaled and in less degree by the exhaled air 
to the olfactory nerves and there by direct chemical action 
arouses the nervous excitation. 

Mixtures and Compensations of Odors. — Mixtures and 
compensations of smells can be demonstrated. For these, 
as for making all quantitative tests of odors, Zwaarde- 
maaker made use of an instrument he called the olfactom- 
eter. In essentials it consists of one tube with a curved 

end to be inserted in the 
nostrils, and of a second 
tube of larger size contain- 
ing an inner hning of the 
substance to be investi- 
gated which slips over the 
former. The amount of 
stimulation is measured by 
the area of the outer tube 
exposed beyond the inner. 
If they are even, the air 
entering the inner tube absorbs none of the substance on 
the outer; and the more the outer projects beyond the inner, 
the more saturated with particles is the air that enters the 
nostril. In the double olfactometer of this sort a tube is ap- 
pKed to each nostril. It is found that if certain substances, 
Peru balsam and iodoform, for example, are applied either to 
the same or different nostrils at the same time, they cancel 
each other and no odor is sensed. Other substances produce 
mixed odors that may or may not be analyzed into their 
components. Xylol and turpentine fuse to form a new odor 
and many others can be mentioned. Certain of these mixed 
odors are given off by simple substances, as can be shown 




Fig. 



66. — Zwaardemaaker's olfactom- 
eter. (From Titchener.) 



KINESTHETIC SENSATIONS i8i 

by the fatigue test. Thus if propionic acid be smelled for 
some time, the original odor will lose one of its components 
and assume a different quality. 

REFERENCES 

Ladd-Wood worth: Principles of Physiological Psychology, 

pp. 304-309. 
Zwaaedemaaker: Physiologic des Geruchs, 1895. 
Titchener: Textbook of Psychology, pp. 1 14-128. 
Henning: Der Geruch, 1916. 

Kinesthetic Sensations 

Kinassthetic Sensations. — To these traditional five 
senses of man, modern science has added a number of others. 
One of the most important is the kinaesthetic, the sense by 
which we appreciate the movements of our own members. 
The muscle sense had a prominent place in the EngHsh 
psychology of the last century, — Thomas Brown and the 
Mills made use of it, — but the first experimental work of 
importance on the subject was carried on by Goldscheider 
in the late eighties of the last century. Goldscheider 
adduced evidence that the more delicate sensitivity to 
movement was in the joints rather than in the muscles, as 
had been earlier supposed. His main bit of evidence for 
this was that the sensation of movement is markedly 
diminished if an induction current is passed through the 
joint as the member is bent. Evidently there are three 
possible sources of sensation for movement, the external 
skin, which must be wrinkled at the joint as it bends, the 
muscles and tendons which are known to be well supphed 
with sensory endings, and the joint. Goldscheider assumed 
on the basis of his experiments that the joint surfaces were 
the organs in spite of the fact that there are known to be 
no sensory nerves ending on the joint surface, and that an 



i82 FUNDAMENTALS OF PSYCHOLOGY 

experiment that he made himself indicated that the mem- 
brane on the joint, the synovial membrane, had a very sKght 
sensitivity. 

By anaesthetizing these various sources of sensation one 
after another, it is possible to determine their order of 
importance in making known the movements. Experi- 
ments are made by placing the member to be tested, usually 
the forearm, on a hinged board, with the joint over the 
hinge, and then raising the board until the movement is 
first noticed. The least movement of the arm which can 
be appreciated is about half a degree. If the external skin 
be anaesthetized, this will not be changed. The skin, then, 
must be less important than the internal sense organs. 
Goldscheider found that if an induction current be passed 
through the joint, there must be a considerable increase in 
the movement before a sensation is produced. He regarded 
this as evidence that the joints were essentially the organs 
of movement. The writer repeated the experiments and 
found that although when the elbow or knee joint was 
anaesthetized by passing an induction current through it 
the sensitivity for movement was reduced, it was also 
reduced quite as much when an induction current was 
passed through the wrist or ankle joint, or the muscles 
near them, and still more reduced when passed through 
both at the same time.^ From this it seems that the essen- 
tial organs in the appreciation of movement are the muscles 
and tendons with the sensory nerve ends that are embedded 
in them. These results have recently been confirmed by 
von Frey^ although he would ascribe an important part 

1 Pillsbury, Does the Sensation of Movement Originate in the Joint? 
Amer. Journ. of Psychology, igoi. Pp. 346-353. 

2 Von Frey, Studien uber den Kraftsinn. Zeitschr. f. Biologic, vol. 68, 
PP- 349-350- 



THE SENSE OF EQUILIBRIUM 183 

to the tactual sensations. This hypothesis is strengthened 
by the histological evidence that the joint surfaces are bare 
of sense organs, and by the fact that careful observation 
indicates that the movement of the elbow is ordinarily 
felt either in the wrist or fingers. Instead, then, of regarding 
the kinaesthetic impressions as coming primarily from 
rubbing of joint surfaces, we may regard the excitation of 
the sensory endings in the muscles and tendons by the con- 
traction of the muscle or the stretching of the tendon as the 
source of our sensations of movement. To this may be 
added as a subsidiary factor the wrinkling of the joint cap- 
sule, which also contains sensory endings. 

These kinaesthetic impressions play a very large part in 
our mental life. It is of course important to know where 
the different members of the body are at any moment. In 
addition to this the kinaesthetic sensations contribute very 
largely to the coloring of other experiences; they guide 
the different movements and constitute an important ele- 
ment in the emotions. We shall have occasion to make 
use of them often in the later chapters. 

The Sense of Equilibrium 

The Static Sense. — Closely related to the kinaesthetic 
sense in function is the sense of equilibrium. This is also a 
sense of relatively recent discovery. In 1872 Crum Brown, 
Breuer, and Mach independently reached the conclusion 
that the portion of the inner ear not used in hearing, the so- 
called vestibular portion of the ear, is closely connected with 
keeping the balance, and with the appreciation of the move- 
ments of the body as a whole. The evidence accumulated 
since is altogether convincing. The organs involved are 
the sacculus, the utriculus, and the semicircular canals, 
named in order from the vestibule. The sacculus is a mem- 



i84 FUNDAMENTALS OF PSYCHOLOGY 

branous sack floating in the lymph contained in an enlarge- 
ment of the bony labyrinth. This opening communicates 
with the vestibule, and the lymph is continuous with the 
lymph of the cochlea. A branch of the vestibular nerve 
enters the sacculus, and ends in hair cells. Among the hairs 
are small crystals of calcium carbonate, the otoliths. The 
utriculus is a similar, somewhat larger sack connected with 
the sacculus by a small opening. The nerve endings are 

Recess, lahyr. 




Duct. cocM. 



Utricul. 



Fig. 67. — The left membranous labyrinth of the ear seen from without, va, 
vp, the anterior and posterior semicircular canals; It, the horizontal canal. The 
relation of the sacculus and utriculus to the cochlea is also shown. 

similar to those of the sacculus. From the utriculus extend 
the semicircular canals, one in each plane of space. They 
have two openings into the utriculus, making possible a 
movement of the lymph through the complete semicircle. 
Near one opening of each canal into the utriculus are small 
swellings, the ampullae. In these end the branches of the 
vestibular nerve that go to each canal. The nerves end 
in long hairs that protrude into the lymph of the ampullae. 
The different branches of the vestibular nerve unite with 
each other and join the cochlear branch to constitute the 
eighth nerve. In the brain stem the two branches have 



THE SENSE OF EQUILIBRIUM 



185 



separate nuclei. The nucleus of the vestibular branch has 
connections primarily with the cerebellum and with the 
nuclei of the motor nerves of the eye. 

The evidence that the function of these organs is primarily 
to keep the bal- 
ance is now mani- 
fold. The earlier 
in ves tigators 
proved that sec- 
tioning a semi- 
circular canal in a 
pigeon disturbed 
its balance and 
the tonus of its 
muscles, and at 
first made it 
stand with the 
head drawn to 
one side. It was 
also shown that 
passing a strong 
electric current 
through the ears 
would produce a 
turning of the 
head. Studies of 
patients v/ith dis- 
eased vestibular organs showed characteristic loss of some 
one function according to the part affected and the length 
of time the disease had lasted. Many of the deaf are also 
defective in keeping the equilibrium. If one registers the 
movements they make when standing erect with eyes closed, 
it is found that they sway much more than the normal 




Fig. 68. — Shows the arrangement of the semicircu- 
lar canals of the pigeon, looking from behind into the 
opened skull. In plane A is the anterior semicircular 
canal; in plane P, the posterior; and in plane E, the 
horizontal of Fig. 67. 



i86 FUNDAMENTALS OF PSYCHOLOGY 



Ampullar hairs 



Hair cells 



individual. It is also found that about half the deaf do 
not have the compensating eye movements, that is, the 
movements of the eyes that make the eyes turn in the 
direction opposed to that taken by the head, that permit 
the eyes to fixate a point refiexly in spite of movements 

of head or body. In 
many cases the ves- 
tibular portion of 
the ear is normal 
when the cochlea is 
affected. 

Streeter has 
shown that if he 
destroys the vestib- 
ular region in the 
tadpole, the frog 
that develops from 
it has no sense of 
position, is as Hkely 
to swim on its back 
or side as right side 
up. Kreidl inserted 
iron filings in the 
otocysts of the cray- 
fish when they were 
opened by the shed- 
ding of the shell, in place of the particles of sand that nor- 
mally find their way into the ca\dties at that time. After 
the new shell was grown he found that if he brought a 
magnet over the crayfish they would at once turn and swim 
on their backs. Evidently the attraction of gravitation for 
the sand particles had been replaced by the magnetic 

1 Streeter, Journal of Experimental Zoology, vol. iii, p. 543. 



Nerve fibres 




Fig. 69. — The hair cells and the hairs that pro- 
trude from the ampuliffi of the semicircular canals 
into the liquid. Movement of the hquid displaces 
the hairs and stimulates the nerve cell. 



THE SENSE OF EQUILIBRIUM 187 

attraction for the iron filings. These various lines of ex- 
perimental evidence, together with the probability raised 
by the close central connection of the nerve with the cere- 
bellum and with oculomotor centres, are conclusive proof 
that the vestibule contains the organ for the static sense, 
and is the source of reflexes for many eye movements and 
for keeping the balance, as well as for keeping the general 
tonus of the muscles. 

The Organs of Equilibration and their Stimuli. — The 
mechanism of the stimulation of the sense organs may be 
made out in a measure from the experimental data and the 
structure of the organs. Movements of the body as a whole 
probably stimulate the sacculus and utriculus primarily. 
As the body moves forward, the otohths are left behind 
for a moment through their own inertia and so move the 
hairs and stimulate the nerves. This excitation occurs only 
at the start; soon the otoliths take on the motion of the 
body and no further excitation occurs. The opposite 
stimulation is given as the motion ceases; the otohths con- 
tinue to move forward under their own inertia for a time 
and produce the same effect as if the person were starting 
backward. This may be noticed as a train comes to a stop. 
For an instant one seems to be starting backwards. Going 
up or down, as in an elevator, also displaces the otohths and 
gives the corresponding sensations. Movements of rota- 
tion and of turning the head in the different planes affect 
the semicircular canals. The hairs in the ampullae are 
probably stimulated by the movements of the hquid and 
these stimulate the corresponding nerves. 

It is a question whether these excitations give rise to a 
sensation of their own or whether they merely excite reflexes 
and these reflexes are appreciated. Violent excitations 
produce sensations of giddiness and finally nausea and vom- 



i88 FUNDAMENTALS OF PSYCHOLOGY 

iting, as in seasickness. Slighter excitations only call out 
movements of the eyes and the movements required to keep 
the balance. The same sensations of giddiness and even 
nausea may be produced by rapid irregular movements of 
the eyes without movements of the body. All of this speaks 
for the view that the sensation of giddiness is not a true 
sensation of the vestibular nerve, but rather a sensation 
from the ahmentary canal, due to reflexes excited by the 
organs of equihbrium. On this theory the vestibular nerve 
excites no pecuKar sensation, but serves to adjust the dif- 
ferent muscles of the body, including primarily the eye 
muscles, to the various movements of the body. The sensa- 
tions arise from the reflexes when they become intense. It 
should be noted that visual sensations, kinaesthetic sensa- 
tions, and sensations due to displacement of the large vis- 
ceral organs also aid in keeping the balance and in appre- 
ciating the movements of the body. The deaf who have 
lost the sensitivity of the vestibule can, by means of these 
other organs, still retain the balance, though less accurately. 

Organic Sensations 

Hunger and Thirst, General Sensibility. — Of the 

sensations from the inner organs, hunger and thirst prob- 
ably bulk largest in the daily hfe of man. Hunger has been 
recently investigated by Carlson and by Cannon.^ They 
find in man and dogs that it is a comparatively transient 
accompaniment of the deprivation of food. During a 
period from three to five days after food is stopped, the 
sensations become continually weaker and gradually prac- 
tically disappear. They are, however, rearoused by sight 
of food or by anything that suggests food. The sensations 
were found to be due to contractions of the walls of the 
1 Cannon, The Physiological Processes in Pain, Hunger, Fear, and Rage. 



ORGANIC SENSATIONS 189 

stomach. Records of these contractions were taken by 
swallowing a rubber sack or balloon with tube attached 
which could be inflated to fill the stomach, and then regis- 
tering, upon a revolving drum, the compressions of the air 
in the balloon. These contractions are particularly vigorous 
when hunger is keenest, and in general run parallel to the 
sensations. Thirst has its seat in the back of the throat. 
It is apparently due to the drying of the membrane there. 
It may be reheved by laving the back of the mouth with 
citric acid or by taking liquid into the system, either 
through the mouth, through an artificial opening into the 
stomach, or directly into the circulation. Each of these 
processes leads to the moistening of the membrane in 
question. In addition to the qualities of sensation discussed, 
there are a vast number of other sensations which fuse in 
the general complex of organic sensibility. It is useless to 
speculate upon their quahty or their number. With the 
advance of science others will undoubtedly be separated 
from the mass and be recognized as separate senses; some 
already have names ascribed to them in popular speech. 
Of these, the more external, of tickhng, pins and needles, 
itching, have been explained in different ways; pins and 
needles by changes in circulation; tickhng by contractions 
in the skin muscles, survivals of the fully developed skin 
muscles in animals,^or, by certain authors, as due to stimula- 
tion of tickle spots, a fifth form of sensory spot in the skin. 
No one of the explanations can be regarded as more than 
hypothetical. The internal sensations are even less known 
and few if any distinctive names can be given. Such names 
as are given refer to particular complexes, such as those 
present in the different emotions, rather than to specific 
sensations. Some of these inner sensations are of the same 
quahty as the cutaneous sensations, and are always fused 



I go FUNDAMENTALS OF PSYCHOLOGY 

with sensations from the contraction of various muscles. 
They are most frequently fused into the vague feelings of 
well-being or ill-being, and are attended to only as signs of 
health or of general bodily state. 

The Doctrine of Specific Energies 

The Doctrine of Specific Energies. — A final problem is 
the bearing of the results so far discussed upon the doctrine 
of specific energies. We have found that law convenient 
as an introduction to the study of sensation, and have used 
it as a guide throughout. But it is now time to determine 
how accurately our hypothesis harmonizes with the facts. 
The doctrine for convenience may be divided into different 
parts. I. A nerve end when stimulated at all always gives 
rise to its own peculiar sensation. 2. There are as many 
nerve ends as there are specifically different sensations. 
3. The quality of the sensation depends upon the char- 
acter of the end organ rather than upon the nature of the 
stimulus. 

If we examine these phases of the doctrine one by one, we 
find that the first holds so far as it is possible to test it at all 
accurately. It applies to the retina, to the end organs on 
the skin and on the tongue, less certainly to the olfactory 
organ. In discussing the problem we distinguish adequate 
from inadequate stimuH. An adequate stimulus is one that 
excites the organ in greatest perfection. Light is an ade- 
quate stimulus for the eye, sound waves for the ear, etc. 
Adequate stimuli give the full number of sense quaHties of 
which the organ is capable. Other stimuH are inadequate. 
The electric current is an inadequate stimulus for all senses, 
pressure an inadequate stimulus for the eye, etc. Each 
of the sense organs mentioned may be excited by one or 
more inadequate stimuH, and when excited responds with 



THE DOCTRINE OF SPECIFIC ENERGIES 191 

a sensation of the quality peculiar to that sense. The num- 
ber of stimuli that will excite the organ and the intensity 
of stimulation required vary from organ to organ and for 
the different sense quahties within the same organ. The 
sensation that arises when the organ is stimulated also 
shows various degrees of approximation to those excited 
by the adequate stimulus. On the skin, most of the organs 
may be excited by several stimuli and give approximately 
the same quaUty as that produced by the adequate stimu- 
lation. The olfactory endings are excited with difficulty 
and then, so far as is known, only by electrical stimuh, and 
the resulting quahty is very uncertain. The location of 
the organ may account in part for the uncertainty of the 
result. The retina has an intermediate position in both 
respects. Mechanical and electrical stimuli at least will 
affect it, and they produce several sensory responses, but 
not the variety or delicacy of effect produced by the Ught 
waves. While the law will not hold with the completeness 
that a firm behever might wish, still it can be said in gen- 
eral that sense organs may be affected by various stimuli, 
and when they respond, if they respond at all, the quahty 
is that ordinarily given by that organ rather than the 
quahty produced by the stimulus in the organ for which 
it is the adequate stimulus. 

The second law is less definitely demonstrable. Except 
on the skin, one cannot prove that each sense quahty has 
a separate nerve end. From what we know of the eye, 
the cones probably have more than one sense quahty, and 
while one might assume that there are different chemical 
substances in each cone, it is hardly likely that there are 
different nerve ends. A case might be made out for separate 
taste buds for each quahty; there is sHght evidence for 
separate organs for each odor. In hearing, the Helmholtz 



192 FUNDAMENTALS OF PSYCHOLOGY 

theory depends for its truth upon the law rather than sub- 
stantiates it. Strictly, then, the statement that there are 
as many qualities as there are sense organs and no more 
holds only for certain senses, and is to be regarded rather 
as a convenient guide to the discussion of sensation than as 
a fully substantiated fact. 

The third principle, that the quaHty of sensation depends 
upon the sense organ excited rather than upon the stimulus, 
holds approximately. Adequate stimuh excite the organ 
at a sUghter intensity and give a richer quahty in most of 
the sense organs. Nevertheless if one were to decide be- 
tween the receiving organ or the external stimulus as the 
determinant of the sensory quahty, the receiving organ 
must be given the more important part. 

There is also a question whether, granted that the sensa- 
tions depend upon the specific characteristics of the nervous 
system, the determinants of the quality are to be found in 
the sense organ or more centrally in the nerves or their 
central connections. The evidence is confhcting from 
sense to sense. According to Nagel^ there is no good evi- 
dence that colors can be excited except from the retina. 
Cutting the optic nerve or turning the eyes sharply to one 
side or the other gives rise to sensations of light, but he 
thinks both probably due to the accompanying pull upon 
the retina. Sensations of taste are with difficulty or not 
at all excited by inadequate stimuh upon the tongue, while 
mechanical stimuli upon the chorda tympani where it 
passes through the middle ear arouse them certainly and at 
comparatively shght intensities. In the skin it is apparently 
the end organ that gives the pecuHar quahty. Pressure 
upon the ulnar nerve gives sensations but not of the distinct 
quahties that may be aroused from the skin. One cannot 

^ Nagel, Handbuch der Physiologic, Vol. Ill, pp. 1-15. 



WEBER'S LAW 193 

decide definitely between sense organ and the more central 
regions. Of the central nervous organs, it seems that the 
nerves themselves are relatively indifferent. They conduct 
in either direction, and sensory nerves may be made to carry 
motor impulses by giving them connections with motor 
structures. Whether the cortical centres have a specific 
function is still an open question. It has been assumed 
by many authorities that the qualities of sensation depend 
upon the parts of the cortex excited. No actual evidence 
for it has been collected and it seems improbable that it 
could be obtained. In general, it may be said that the doc- 
trine of specific energies of sensory ends lacks much of com- 
plete demonstration, but that what data we have tend to 
support rather than to refute it. On disputed points evi- 
dence is wanting rather than opposed. 

Studies in Sensation Intensities. — Weber's Law 

Sensation intensities offer an entirely different problem 
from quahties. QuaHties, as we have seen, are ordinarily 
named, may be referred in some cases to sense organs, offer 
points of discrimination that may be recalled in memory, — 
in general they stand out for themselves. Intensities, on 
the contrary, have none of these characteristics. We think 
of a sound as very faint, moderately or very loud, but that 
is all. Intensities have no real designations, and cannot be 
remembered at all accurately. It is perhaps not one-tenth 
as bright in this room to-day as it was when last the sun 
shone, but you do not appreciate the difference accurately. 
You think of this as a moderately dark day, but have Httle 
idea how much darker than yesterday. The same holds of 
weights. Most persons have great difficulty in deciding 
whether a package of an unknown substance weighs one 
pound or two, and would be altogether at a loss to 



194 FUNDAMENTALS OF PSYCHOLOGY 

decide whether more energy was exerted on the ear by a 
telephone held close to it or by a steam whistle at a 
distance. 

Measurements of Sensation. — It has long been a prob- 
lem among psychologists as to how intensities may be 
treated. The modern discussion of the matter may be said 
to date back to Fechner, who thought it would be possible 
to obtain a unit for the measurement of sensation intensities 
analogous to those employed in physical measurements. 
His assumption was that the barely distinguishable sensa- 
tion difference, the difference limen as he called it, might be 
made a unit and any given sensation might be measured in 
terms of the number of such units it contained. This as- 
sumed that the only judgments that may be passed on 
intensities are that the sensation is or is not present, 
or that it is greater or less than another. The amount 
of sensation intensity that may be just noticed, the limen, 
was chosen by Fechner as the zero point in his scale. If 
one should start with the faintest sensation that comes 
to consciousness, and determine the addition that can just 
be noticed, the liminal sensation might be called sensa- 
tion number one; the just noticeably different sensation, 
sensation number two; and if one should continue the 
process, it would be possible to determine the entire 
number of differences that could be noted in the series 
of sensations, and thus the entire number of sensation 
intensities in any sense department. It would also be 
possible to measure any sensation by the number of these 
unit intensities that were contained in it. Unfortunately, 
however, the facts are by no means so simple as this theory 
would assume. The least intensity that can be noticed is 
not fixed even for the same individual, and the number of 
units that can be noticed is also variable. In consequence, 



WEBER'S LAW 195 

this scheme, attractive as it is in theory, has never been 
and apparently cannot be applied in practice. 

Weber's Law. — Out of the very large number of experi- 
ments devoted to these measurements, a law has developed 
that is of great interest. Very briefly, it has been found 
that the size of the just noticeable increment is not the same 
for all intensities, but increases with the absolute intensity 
of the stimulus, and bears a constant ratio to that intensity. 
Thus Weber found that if a weight of 32 ounces were lifted, 
it could be noted that 30 ounces was just less, while if 32 
drachms were lifted, 30 drachms could just be noticed to be 
different. A difference of a fifteenth of the total weight 
could be noted whether the units were ounces or drachms. 
These relatively crude experiments have been repeated 
and improved upon by a number of later workers, Fechner 
in particular, and show the same general law. The fraction 
of the total intensity that may be just noticed varies from 
one sense to another, but holds with fair accuracy for the 
same sense. The values range from approximately tfo for 
sight to one-third or one-fourth for smell. In giving these 
values, it should not be assumed that the just noticeable 
difference is absolutely constant even under constant 
objective conditions or under conditions that are as nearly 
constant as can be obtained. Differences in the order in 
which stimuli to be compared are given, in the degrees of 
attention at different times, and in the way in which the 
suggestions that may be given unintentionally may work, 
all have an influence upon the determination of the dif- 
ference limen. In consequence, it is not often that two 
consecutive experiments will give the same result. All 
values given are averages obtained with the same indi- 
vidual, and where several values are given it is assumed that 
the two are extremes for the subjects used. Occasionally the 



196 FUNDAMENTALS OF PSYCHOLOGY 

values obtained from different observers will be averaged, 
but this is not at present regarded as advisable. The results 
are not to be regarded, as in physics, as constant values that 
are obscured by the varying conditions of observations, but 
as fundamental differences due to the differences between 
individuals. 

Departures from Weber's Law. — It is also true that the 
fraction varies for the different absolute intensities. It is 
always greater for the extreme intensities, and even within 
what may be called the mean values, there is often a gradual 
change. The first fact can be seen in many of the simple 
phenomena of daily life. The increase in the least noticeable 
difference at maximum intensities is illustrated in the diffi- 
culty in reading when the sun is shining on the page, as 
the difficulty in reading in faint light illustrates the increase 
of the relative difference at the lower range of intensities. 
The relative amount of light reflected and absorbed is the 
same at all intensities, but the relative difference that may 
be discriminated is much greater at the extremes of absolute 
intensities. Were relative differences discernible with equal 
ease at all intensities, one could read as readily by moon- 
light as by electric light, and in the glare of the sun as well 
as in the shade. 

The values that have been obtained in the more important 
senses range for vision from eV to tws for different observers 
and different intensities. For hearing, Wien, using tele- 
phone tones, obtained a fraction of i to i; for pressures, 
values have been obtained from iV to iV, depending upon 
the part of the body stimulated. Lifted weights give a much 
smaller value than passive pressure, from ^ to tq-o", according 
to Biedermann and Lowitt, according to Weber xcr- Taste, 
smell, and temperature all offer difficulties in the technique, 
and the results are correspondingly unsatisfactory. The 



WEBER'S LAW 197 

values of the fraction for these senses are generally given 
as ranging from i to i. 

The Limen for Sensation. — The results of the investiga- 
tions of the least intensities that can be perceived, the abso- 
lute sensation limen, have also been determined for certain 
senses with a satisfactory degree of accuracy. For sight 
and sound the values can be given in terms of absolute units. 
Langley found that the eye was sensitive to Kght waves 
that exerted an energy of .00000003 erg. Wien found that 
the ear would respond to still smaller values : from .000004 
erg for tones of 50 V D per second to .0000000000000005 
erg for tones of 3200 V D per second. For pressure, the 
most reHable results are those given by von Frey.^ He 
found the energy required to excite a hair to be about 5V of 
an erg, and to excite a pressure spot on the skin about i 
of an erg. Values obtained for other senses have relatively 
little meaning, as they cannot be stated in terms of energy. 

Theories of Weber's Law. — It can be asserted, then, 
that within limits Weber's law holds. Differences in two 
stimuH are noticed more easily when the absolute stimuH 
are low than when they are high, and the addition that 
can just be appreciated is a constant fraction of the stimulus 
already present. The explanations of this law fall into three 
groups. Wundt holds that the law has a purely mental 
basis, that it is but one expression of the general law of 
relativity ; all things are estimated in terms of other things 
that may be in consciousness at the moment. This is 
merely a restatement of the law rather than an explanation. 
Fechner regarded the law as an expression of the general 
relation between body and mind. These were two phases 
of a single substance for him, Hke the inside and outside 
of a circle, and in some way not made clear, stimuli that 

^ Von Frey, Zeitschrift f. Biologic, vol. Ixx, p. 333. 



198 FUNDAMENTALS OF PSYCHOLOGY 

increase in a geometrical ratio produce an increase in mind 
in an arithmetical ratio. A third theory, developed in large 
degree by G. E. Miiller, explains the law as due to the loss 
in intensity that a nerve impulse undergoes in passing 
through the nervous system itself. That such a loss does 
take place is suggested by the experiments of Waller with 
the optic nerve and retina of a frog. The current of action 
of the nerve excited by different intensities of light upon 
the retina was measured and it was found that the current 
of action was related to the intensities of stimulus in the 
arithmetical-geometrical ratio. Miiller asserts that the 
more intense the stimulus, the more opposition is offered 
to its passage through the nervous system, and in conse- 
quence the more is lost, — a smaller proportion reaches the 
brain. If the amount lost — and so the amount retained 
— is proportional to the absolute intensity of the stimulus, 
the demands of Weber's law are satisfied. Ebbinghaus has 
suggested that this increased loss can be explained on the 
assumption that there are in the nerve chemical substances 
which decompose with different degrees of difficulty. The 
less intense stimuli use up the more readily decomposable 
elements, and hence produce a relatively great effect on 
consciousness, and the stimulus must exhaust an increas- 
ingly greater amount of energy in affecting the components 
next higher in the degree of difficulty of decomposition. 
Whatever the detailed explanations, the facts available 
indicate that the law is due to the increasing resistance 
offered in the nervous system to the transmission of the 
more intense nerve impulses, that the explanation is physi- 
ological rather than psychophysical or purely psycho- 
logical. 1 

1 Titchener, Manual of Psychology, Instructor's Manual. Quantitative. 



CHAPTER VI 

THE ORIGINAL NATURE OF MAN, AND THE 
MEANS OF MODIFYING BEHAVIOR 

We have now summarized the more important facts which 
are preliminary to any study either of the behavior of man 
or of his consciousness. The nervous system makes possible 
all activity; and the sense organs through their stimulations 
supply the incentives for all movement and also provide the 
materials that are manipulated in the acquisition of knowl- 
edge of any type. The nervous system has within it at 
birth the connections that make possible the instincts and 
reflexes; potentially it has the capacity for forming the 
connections upon which depend all acquisition of habits, 
and the form of learning which we popularly call 
memory. 

Nature and Nurture. — When we turn from the discus- 
sion of the physiological structures, which must be under- 
stood prior to any study of psychology, to the actual inves- 
tigation and explanation of man's activities and hfe, there 
are two opposing tendencies which must be taken into con- 
sideration in the explanation of every phase of conduct 
and of thought. These are known roughly as instinct and 
habit, or even more generally as nature and nurture. 
Briefly these terms mean that the man is determined in his 
responses and in his thinking by characteristics inherited 
from his immediate ancestors and from the race as a whole, 
and by certain other characteristics developed by the 
environment in which he Kves. The one is present at birth 

199 



200 FUNDAMENTALS OF PSYCHOLOGY 

or is the immediate outcome of the growth of his nervous 
system; the other is a direct product of living and learning, 
of his adaptation to the world about him. These two op- 
posing groups of forces are frequently difficult to distinguish, 
and they almost always interact in determining both the 
general capacity of the individual and the nature of his 
specific responses to any given situation. Still they must 
be regarded as distinct in our discussion. 

The native endowment of the individual includes both 
the capacities distinguishable at birth and those which are 
to develop later. If one look at a new-born infant and study 
its responses, one sees in it relatively Httle of the powers 
that it is to develop. An occasional cry, a few reaching 
movements, and the reactions of nursing, give about the 
only evidence of intelligence. There is no way of deter- 
mining at this stage what the future capacity is to be. An 
observer could not tell a future Darwin from a possible 
criminal or imbecile by any of the tests known to science, 
if he did not have a knowledge of the heredity of the child. 
Even an acquaintance with the heredity gives only the 
possibility, not complete assurance, of the career that is to 
be. Nevertheless we must believe that a large part of the 
accompHshment of the child is already determined. Train- 
ing and the effect of environment wUl serve to bring out 
what is already there, but in the absence of certain as yet 
unknown characteristics of the nervous system, no amount 
of training or stimulation would suffice to produce great 
ability. 

Two fundamental forms of native endowment may be 
distinguished. One determines the specific responses of 
all individuals of a species to given situations; these are 
the reflexes and instincts. The other determines the more 
general capacity for learning and response, the intelligence, 



INTELLIGENCE, TEMPERAMENT, WILL 201 

temperament, and disposition of the individual. The 
reflexes and instincts we regard as the forces that make all 
individuals respond in approximately the same way; the 
other forms of equipment give rise to the differences be- 
tween individuals. Both are due to heredity. The first 
group designates the inherited similarities in response; 
the second, the inherited differences. Another distinction 
is that the instincts and reflexes show themselves in actual 
responses, while the other terms indicate only capacities 
for responses or for learning, or the tendencies to emo- 
tion. 

Intelligence, Temperament, Will. — We distinguish three 
ways in which individuals may differ in capacity : in intelli- 
gence, in temperament — or the liability to certain emo- 
tions, and in the volitional characteristics of action — the 
qualities of the will. The definition of these terms has gone 
little farther in psychology than in popular usage. By 
intelligence we mean the ability to think to good effect, to 
appreciate situations, and easily find the solution for the 
difficulties they present, to appreciate ends and to be able 
to work consistently towards those ends. In practice, in- 
telligence goes very closely hand in hand with the ability 
to maintain one's self in a given environment, physical and 
social. The temperaments are not clearly differentiated 
although all admit that both for scientific classification and 
for the treatment of mental diseases, it is desirable to push 
our analysis farther and to secure tests that shall measure 
temperamental differences. The volitional characteristics 
are also important, but we know only that differences in 
the ability or willingness to work persistently to a desired 
end influence markedly the success of individuals of the 
same intelligence. 



202 FUNDAMENTALS OF PSYCHOLOGY 

Intelligence Tests 

Binet Tests. — Tests of intelligence have been developed 
in great number and several of them have been standardized 
to the point where the wider differences may be measured 
with considerable accuracy. All are alike in requiring the 
individual to be tested to carry through a number of rela- 
tively simple mental and physical operations in which he 
may be rated for quickness and accuracy. The two tests 
which have had the widest use and are in many ways best 
adapted to the purpose are the Binet tests and the tests 
developed for the examination of the intelligence of the 
United States soldiers in the World War and consequently 
known as the Army Tests. The Binet tests were developed 
on the assumption, which the outcome verified in general, 
that one might measure the intelligence of any one below 
the average intelligence, by comparing his accomplishment 
in a series of tests with the accomplishment of a child of 
some given age. It was assumed that the child begins with 
approximately zero intelligence, and then passes through 
all degrees until, if an average child, he reaches average 
adult inteUigence. Binet devised a group of tests for each 
age, which the average child of that age could just pass. 
These were tested on a large number of children and in 
actual practice arranged in groups on the basis of the results 
obtained. The tests ranged in difficulty from naming the 
parts of the face and simple objects, to defining abstract 
words and stating the difference between a king and a 
president, on to complicated arithmetical puzzles. Much 
depends throughout upon memory for immediately pre- 
ceding events, upon the amount learned from what is as- 
sumed to be the environment of the normal child, and upon 
ability to appreciate situations and apply simple remedies in 



INTELLIGENCE TESTS 203 

case of difficulty. One test alone would have little signifi- 
cance, but a number taken together give a fairly accurate 
idea of the capacity of the individual. 

The Mental Age and Intelligence Quotient. — Binet's 
most important contribution to the methods of testing was 
in using the capacity of children of different ages as a stand- 
ard of comparison. After one has discovered which of the 
group of tests the individual can pass, one has a measure. 
of his intelligence in years, which is now generally called 
his mental age. If of average ability, his mental age and his 
chronological age are the same; if he has developed more 
slowly than the average child he will be retarded by one or 
more years. The mental age gives an immediate indication 
of the intelligence of an adult. The mental age scale is 
applicable readily and satisfactorily to children and to 
defective adults. Since the average child reaches his 
maximum development at thirteen, it is obvious that the 
measure cannot be used for adults of more than average 
ability. Recently in revising the scale, Terman suggested 
that one could state the intelligence of an individual irre- 
spective of his actual age, if one used the ratio of mental 
age to chronological age as the index of intelligence. If 
one divide the mental age by the chronological age, one 
obtains what he calls the intelligence quotient, usually abbre- 
viated as the I. Q. The I. Q. of the average individual is 
100. The justification for using the ratio of mental to 
chronological age is that tests show that this ratio remains 
fairly constant throughout life. If a child is one year 
behind at four, he will usually be two years behind at eight 
and three years behind at twelve. His I. Q. would be con- 
stant at 75. If a child were one year ahead at five, he would 
similarly be two years ahead at ten and would have an 
intelHgence quotient of 120. One limitation of the method 



204 FUNDAMENTALS OF PSYCHOLOGY 

is that only a young child can make a very high rank. The 
highest age for which tests are given by Terman is twenty. 
In consequence, a child of sixteen would be limited to an 
I. Q. of 1 25, while a ten-year-old might make 200. The tests 
beyond fourteen have little relation to the accomplishments 
of actual children, as few children reach that level. 

The Distribution of Intelligence. — So far as results go, 
intelHgence seems to be distributed in accordance with 




Fig. 70. — The distribution of stature among French soldiers. The distances 
on the horizontal axis indicate the height in centimetres, on the vertical axis, the 
number of men of heights between the figures printed below the line. (From Ber- 
tillon: Instructions signaletiques.) 

what the mathematician calls the normal frequency curve. 
It is the curve that results if one plots a large number of 
measurements of any kind on unselected individuals. 
Figure 70 shows the curve that results from plotting the 
heights of a thousand French soldiers, indicating the height 
in centimeters above 100 on the base line and the number 
of individuals who are of the given stature on the vertical 
distance. The average in this case was 164^ cm. There 
are just as many who are taller as shorter, and the greater 
the distance from the average the fewer are the individuals 
represented. There are 236 between 163 and 166, but only 



INTELLIGENCE TESTS 205 

10 each who are less than 141 cm. or more than 180 cm. tall. 
Terman found that intelligence is distributed in the same 
way. About 60 per cent fall within ten points on either side 
of the average, and have an intelKgence quotient between 
90 and no. These are the average individuals. There are 
about 14 per cent between 80 and 90, and between no 
and 120; about 5 per cent each in the next range of ten 
points to 70 below and 130 above; and i per cent below a 
quotient of 70 and with 130 and above. Those below 70 
are ordinarily counted as feeble-minded; that is they are 
sufficiently deficient to be Kkely to become a charge on the 
community, while those above 130 are exceptional, and 
are ranked by Terman as geniuses or near geniuses. 

The Army Tests. — In the Army Tests the method of 
measuring capacity is to compare the accompHshment of 
the individual with the performance of a large number of 
other individuals and give him a rating relative to the group. 
It consists of a series of questions to test arithmetical sldll, 
general information, abiHty to understand and follow direc- 
tions and to comprehend different relations. It could be 
given in less than an hour to two hundred or more men at 
once, and as it was given to a milHon and three quarter men, 
the results sufficed to give an excellent idea of the distribu- 
tion of intelhgence in the general population. Like the 
Terman test, it shows that the distribution of intelligence 
follows the normal frequency curve. The total possible 
score was 212. On both tests the intelligence was found 
to be symmetrically distributed. About 4 per cent made a 
better score than 140 and about 7 per cent made a lower 
score than 14. The first were designated as an A group, 
the lower as an E; similar intermediate grades were made. 
The men of the A group were found to be of intelligence 
suited for high command, provided they had the emotional 



2o6 FUNDAMENTALS OF PSYCHOLOGY 

and volitional characteristics. The lowest group was dis- 
missed from the service, or, more usually, transferred to a 
service battalion, as they were of no military value. In 
civihan life the A group men were found to be from the pro- 
fessions and to have been the successful men, while the D 
and E group men were from the ranks of common labor 
and had had httle success in that role. On the whole it was 
found that the degree of intelligence as shown in the tests 
was closely correlated with the grade that had been reached 
in the educational system. The E men had seldom gone 
beyond the third grade, while many of the A men were 
college men. This does not mean that the education had 
necessarily made them intelligent, but that their intelligence 
had made it possible for them to go as far as they did in the 
school system. The results of the tests as a whole are im- 
portant in showing the wide differences in the intelligence 
of the general population, and also in indicating the natural 
selective agencies that roughly adjust the individuals of 
different intelligence to the callings that are best suited to 
their abilities. 

The results of the tests are important psychologically in 
indicating how differently we must treat different individ- 
uals in psychological experiments. The general laws of 
mental action are the same for all, but the amount that can 
be expected of individuals will differ greatly. The results 
of the army tests and of the Binet tests taken together indi- 
cate that intelHgence is distributed very much as stature is. 
There are a large number of average men. About 68 per 
cent of all fell in the C grade on the army scale, as most 
men would fall within three inches of the average in height. 
The farther away from the average any measurement Hes, 
the smaller the number of individuals who fall in the class. 
Practically, the results are of value in indicating the limita- 



CHARACTER TESTS 207 

tions of certain individuals for the higher types of training 
and even for Hfe in society. The schools have found the 
tests of value in sorting out those who are incapable of 
doing good work or of keeping up with the grade. The worst 
must be given a special kind of training; and the better 
types, when put by themselves, can be taught by different 
methods and permitted to learn at a faster rate. Tests of 
prisoners in civiUan Hfe, particularly the juvenile prisoners, 
have shown that many of them are below normal mentally, 
as are also many of the paupers and others who have diffi- 
culty in maintaining themselves. Recognition of the differ- 
ences in intelligence is necessary to an understanding of 
many social problems. 

Character Tests 

Investigations of Character. — Differences in emotional 
and volitional characteristics undoubtedly exist, but accu- 
rate measurements have not been made of them. So far 
no scheme of measurement has been devised, much as that 
is needed, particularly by the speciaKst in nervous diseases, 
since emotional disturbances are strikingly frequent in 
the causation of such troubles. An investigation by Webb 
sought to determine the differences by having the degree 
in which individuals possess certain traits rated by judges 
who knew them well. He chose certain characters that are 
fairly easy to note, such as readiness to anger, eagerness for 
admiration, bodily activity in the pursuit of pleasure, per- 
sistence of motives, continuance towards a goal in spite of 
obstacles, trustworthiness, conscientiousness, etc. He found 
that certain of these traits correlated closely among them- 
selves. They could be divided into two classes : a desirable 
group, including persistence of motives that lead towards 
a remote goal, quick recovery from anger, conscientiousness, 



2o8 FUNDAMENTALS OF PSYCHOLOGY 

which were Hkely to be possessed in approximately the same 
degree by the same individuals; and an undesirable group, 
exhibiting readiness to anger, eagerness for admiration, and 
bodily activity in the pursuit of pleasure. If a man stood 
high in one he was likely to be ranked low in the other group. 
These traits, too, were likely to have a relation to the pos- 
session of intelligence. A man who possessed the desirable 
group in considerable measure was also likely to stand high 
in intelligence, while a man who had the undesirable group 
in considerable amount would be lower in intelligence. It 
is obvious that both the emotional and volitional character- 
istics would be important factors in determining the success 
of an individual in tests or in obtaining grades, but the 
investigations endeavored to distinguish between the quali- 
ties. The results indicate a condition which is found fairly 
generally in the study of individual differences — that 
desirable qualities of all kinds go together. There is no 
compensation in the bestowal of traits. A man who stands 
well in one desirable quality will stand well in all, and vice 
versa. There are occasional men with good intelligence 
who fail because of lack of persistence or of social adapta- 
bility. Fortunately these are the exception rather than 
the rule. 

Individual Differences 

The Coefficient of Correlation. — In discussions of statis- 
tical matters it is frequently necessary to indicate the degree 
of similarity between individuals and the likelihood of the 
appearance of different traits in conjunction. This relation 
can be stated in a single number by the coefficient of corre- 
lation. If we have two traits and desire to determine the 
degree in which they are likely to go together in individuals, 
we can measure the relation and state it by the coefficient 



INDIVIDUAL DIFFERENCES 209 

of correlation. For example, in order to determine the rela- 
tion between intelligence and stature, one may measure the 
degree of connection by arranging a large number of indi- 
viduals in their order with reference to each of these charac- 
ters and determining the relative ranking in each. Should 
there be a complete identity between the two traits, the 
individual who ranked first in one would be first in the other ; 
the individual who was second in one would be second in 
the other, etc. If this relation held, we would have a 
coefficient of correlation of i.o. On the other hand, were 
height in some way inimical to intelligence, we might find 
that the shortest individual was most intelligent, the next 
shortest ranked second in intelligence, and so on. In the 
case of such a relation, we would have a coefficient of — i.o. 
Such absolute agreement is never found. What we do find 
is that many of the men who stand high in one, will stand 
high in the other also; while in the case of negative corre- 
lations, many or most of the men who are above the average 
in one will be below average in the other. These are repre- 
sented by numbers between zero and 1.0 or between zero 
and minus 1.0; the nearer 1.0, plus or minus, the greater 
the degree of similarity or dissimilarity. The methods of 
obtaining the exact values may be found in treatises on 
statistical method, Yule's " Theory of Statistics," for ex- 
ample. A coefficient of correlation seldom is above .90. One 
below 0.35 indicates relatively little similarity, unless ob- 
tained from a very large number of individuals. Such a 
correlation as that between height and standing in mental 
tests would be possibly 0.5-0.10. It seems to be positive 
but so slight as to indicate nothing. The correlations 
between common sense and readiness to anger, in Webb's 
work, was -.53; while that between common sense and 
originality was 0.84. 



2IO FUNDAMENTALS OF PSYCHOLOGY 

The Causes of Individual Differences. — When we raise 
the question of the origin of the differences in intelhgence 
or in temperament, we find that there are two possible 
answers. On the one hand we might assume that all was 
due to heredity or that all was due to training. The other 
answer would involve both influences, attributing part to 
heredity and part to training; if this were the case, the 
problem would be complicated by determining what the 
share of each might be. The evidence is largely supplied 
by statistical studies. 

Most work has been done upon the origin of intelligence. 
The lack of intelligence or feeble-mindedness seems, from 
Goddard's results, to be a recessive trait, which follows the 
laws of Mendelian inheritance quite as accurately as do the 
transmission of colors in plants, or shagginess in the guinea 
pig. Goddard traced this trait in several hundred families 
in New Jersey and found that one could predict the appear- 
ance of feeble-mindedness in the children with the same 
accuracy that one could predict the shape of the leaf from 
crosses of plants. 

Studies of the intelligence of school children by the Binet 
tests indicate that the intelligence of children who come from 
the better homes is about a year higher on the average than 
is that of those who come from poorer homes. One might 
attribute this to training as well as to inheritance. If we 
assume that the individual with the better home and social 
standing is more intelligent and has reached his position 
because of that intelligence, the parent who is responsible 
for the heredity of the child is also responsible for his training. 
That it is heredity rather than training is shown from the fact 
that occasionally one will find a child of high intelligence in a 
poor home, while placing the child of unintelligent parents 
under the best of tiaining will not increase his intelligence. 



INDIVIDUAL DIFFERENCES 211 

Studies of heredity as shown in the biographies of eminent 
men indicate not merely that intelhgence in general is 
inherited, but also that specific types of intelligence are 
transmitted. Galton traced the ancestry and descendants 
of eminent Britons of all calKngs, and found that children 
of distinguished men had a very much greater chance of 
being eminent themselves than did the child of average 
parents. Sons of justices were Hkely themselves to be dis- 
tinguished jurists, sons of distinguished scientists were 
likely to be scientists of high rank, and children of artists 
were frequently successful in art. Wood, in a similar study 
of royal personages, found marked tendencies to the inherit- 
ance of abilities and of defects. One might argue that the 
specific direction of the interests of the child of the com- 
moner might be dependent upon living with the parents 
and the opportunities that were impHed by that. Un- 
doubtedly there is some element of environment included 
in the influences that determined the men whom Galton 
studied. In royalty this factor would be reduced, since, 
so Wood argues, the environment for all royal children is 
approximately the same. Nevertheless the traits of the 
parents can be traced very clearly in the offspring through 
a number of generations. 

Another statistical study of inheritance by Pearson con- 
firms the result. Pearson asked teachers in all parts of 
England to estimate the standing of brothers and sisters 
with reference to easily described traits, and then calcu- 
lated the coefhcient of correlation for the traits in pairs of 
brothers and sisters. He included ability, vivacity, con- 
scientiousness, temper, and assertiveness, among his traits. 
He found a coefficient of correlation between children of the 
same parent of about 0.50. This is approximately the same 
as the coefficient for different physical measurements. In 



212 FUNDAMENTALS OF PSYCHOLOGY 

the rough, it means that mental characters are as Hkely to 
be inherited as are physical characters. It will be noticed 
that several of his traits belong in the emotional and voli- 
tional group. This so far tends to confirm common observa- 
tion that these are inherited as well as, and in approximately 
the same degree as, the intellectual differences. Taken to- 
gether the evidence is conclusive that differences in mental 
capacities and in voHtional and emotional disposition are 
specific heredities from the immediate parents. 

Habit Formation 

Instinct and Habit. — On the other hand there are groups 
of characteristics which are also inherited that contribute 
to make the individuals similar. These are the instincts. 
While present in different degrees in different individuals, 
they are represented in all individuals and may be con- 
sidered the factors that serve to produce uniformity in the 
race as a whole. Very briefly we may assert that similarity 
in response to the same stimulation, the similarities in aims 
and in mental activities when not due to similar education 
or to Kving in the same environment, are to be ascribed to 
instinct. These instinctive responses range from those which 
are fundamental to the life of the organism and serve to keep 
the individual alive until he learns to take care of himself, to 
the appreciation of the essential or desirable in external 
stimulation and in his own aims. The definite study of the 
instincts in their origin and effects we may leave to the 
next chapter. Suffice it here to indicate that there are these 
movements and forces in the control of behavior and mental 
life in general which are due to the connections innate in 
the nervous system. In discussing the reflexes in the 
chapter on the nervous system, it was seen that the simple 
actions were determined by the ready-made connections 



INSTINCT AND HABIT 213 

between different neurones at the synapses. The instincts 
have the same general explanation. They, too, are the 
result of the openness of synapses at birth. The difference 
between the two is, first, that the instinct is usually a larger 
group of movements tied together in a single complex 
whole; secondly, that the movements are characterized 
by their cooperation to the attainment of a definite end; 
and in the third place, the movements involved in the 
instinct may be more variable, the end is apparently 
determined, but the movements by which the end is at- 
tained may be varied with the circumstances or through the 
learning of the individual. 

The Formation of Habits. — The other factor in the life 
of the individual which requires preHminary mention here 
is the formation of habits. On the motor or behavior side 
this is the complement of instinctive activity. Certain of 
the movements of the organism are as fixed as the move- 
ments of a machine, at least of a machine that is loose in 
the gearings and as wobbly and uncertain in its movements 
as the worst conceivable machine that will run at all. By 
far the greater number, however, are adjusted to the sepa- 
rate stimuh by a series of tentative movements, and become 
fixed, if at all, only after a number of trials. The higher 
the animal, on the whole, the smaller the proportion of 
responses that are determined by instinct and the larger 
the number that must be acquired by the individual him- 
self. 

Learning is by Trial and Error. — This process of learn- 
ing is always by a series of trials with numerous failures and 
long- delayed successes which only gradually approximate 
the end desired. This is known as the process of trial and 
error. Fundamentally it is probable that each separate 
movement is prepared by an open connection or connections 



214 FUNDAMENTALS OF PSYCHOLOGY 

in the nervous system. However, so many paths are open 
that many different responses are made in succession to the 
same stimulus, and the apparent result is that chance 
determines what the first reaction shall be and the order in 
which it shall be followed by other responses. 

Studies on animals under experimental conditions indicate 
very clearly the nature of the process. If a hungry cat be 
put into a box with a door supplied with a catch which 
can be opened from the inside, and a bit of fish placed near, 
the following series of learning processes will be noted in 
typical cases. Biting the catch, and biting without definite 
object near the door and at all other places that look 
promising, will be succeeded by scratching, and even by 
cries. Sooner or later some one of these movements is 
pretty sure to open the door and permit the cat to walk out. 
Learning in animals is seldom complete with one per- 
formance. If the cat be put back, it will have to go through 
a similar series of uncertain movements before it gets out 
again. The time required for escape will be lessened at 
each trial, until finally it will make the correct response as 
soon as it is put into the cage. Learning by the child also 
follows the method of trial and error. When the baby learns 
to creep, the first movement is by chance. Some children 
make their first movements by hitching forward as they 
sit up. If this is repeated sufficiently often it may become 
established as a habit, and unless the regular crawling move- 
ment or some other more effective means of locomotion 
happens to be hit upon, the child may use that alone until 
he learns to walk. Some children hit first upon the series 
of movements that will push them backwards — occa- 
sionally one will develop the habit of rolling over. Which- 
ever develops first will be used until a new and more satis- 
factory method is hit upon. In many cases the first method, 



INSTINCT AND HABIT 215 

even if awkward, will be continued until the child begins 
to learn to walk. 

This trial and error method is followed in the acquirement 
of every kind of movement; it persists to the acquisition 
of the most important and complicated movements of adult 
life. From these simplest first movements through to 
learning a complicated industrial process or a new game of 
skill, the process of learning is one of chance movements 
and elimination of the unsuccessful attempts. 

Learning as a Nervous Process. — If we analyze the 
mechanism of the process a little more closely, we can see 
that the requirements are: first that the individual shall 
have a large number of possible movements at command and 
shall know when the desired object is attained, or possibly 
shall have the capacity for discriminating between the 
beneficial and non-beneficial, either in advance of the 
movement or after the result has been gained. The first 
capacity is due to the spread of the impulse from the sen- 
sory neurones first aroused to as many motor neurones as 
possible. This spread through the untrodden ways of the 
cerebral cortex is very much like the formation of associa- 
tion, save that there is not even the simultaneous activity 
of some other area to guide the course. Every impulse of 
even moderate strength seems to pass over into motor 
discharge. When a sensory neurone or group of sensory 
neurones is aroused, the impulse tends to spread to motor 
paths, even if there has been no previous excitation of that 
group of neurones or sense organs. It has sometimes been 
suggested that each response must have been developed in 
the brain previous to birth, — must be in part of instinctive 
origin, — but the number of apparently new combinations 
makes it seem that many parts of the cortex have open 
pathways between them over which the impulse may take 



2i6 FUNDAMENTALS OF PSYCHOLOGY 

its course. The many alternative paths make learning 
possible. 

Selection of Habits Determined by Instincts. — When 
a stimulus affects the sense organ, one group or series of 
synapses after another will be opened, and a corresponding 
movement made, until a more satisfactory condition is 
attained; that is, until the stimulus, if unpleasant, has 
been removed or a more complete stimulation by a pleasant 
stimulus has been obtained. These successive paths are 
opened in the order of permeability of the synapses. The 
determination of what response shall be accepted and 
repeated until it becomes a habit is the essential phase of 
the whole process. The selection is fundamentally innate 
or instinctive in character. What shall seem suitable to 
the individual depends upon his inherited disposition, 
influenced to some extent possibly by his training. When 
the result of a movement is pleasing, either in general or in 
the particular setting in which it occurs, it will be repeated. 
With repetition it will become a habit. In this way the 
control of habit formation is exercised through instinct. 
Since many movements that are ordinarily called instincts 
are not perfect at the first performance and need a number 
of trials before they reach perfection, it is evident that 
most of what we call instincts are definitely similar to these 
habitual processes. Both belong to the same class, but lie 
at opposite extremes. All movement depends upon both 
instinct and learning. One element may greatly predomi- 
nate over the other. After the response that gains satis- 
factory results chances to be made, it will be repeated until 
the synapses that lead to it will be more completely open 
than any of the others. When the habit of making this 
response is established the particular movement will always 
respond to the given stimulus. 



INSTINCT AND HABIT 217 

Pleasure a Guide to Learning. — The modus operandi 
of the instinct in the formation of habit is not altogether 
agreed upon. In part it seems that the mere pleasantness 
of the result itself serves to facilitate learning and so leads to 
habit formation. At times it seems that the mere pleasant- 
ness makes a response whose result is pleasing more likely 
to be repeated, and so the learning is due to the frequency 
,of repetition alone. In other instances it seems that the 
pleasure itself serves to make the pleasant response more 
permanent, to have a greater effect upon the synapses than 
the unpleasant. Certain it is that the pleasant response 
becomes established, while the unpleasant is eliminated. 
One element in the process may be the frequency of repeti- 
tion when a stimulus recurs that has evoked a response with 
a pleasant result. The old pleasure-giving movement will 
be repeated, while the unpleasant response evoked by a 
stimulus will be checked when it reappears later. This 
leads to a more frequent repetition of the pleasant response 
than of the unpleasant. Often this takes the form of one 
movement when the stimulus itself is pleasant, and of 
another when it is unpleasant. Usually withdrawal comes 
with displeasure, approach with pleasure. A case of 
opposed response is illustrated by the learning to peck and 
swallow of the moor chick reported by Lloyd Morgan. The 
chick at first pecks at all small objects. When a disagreeable 
one reaches the mouth it is ejected, while the pleasant one 
will be swallowed. After a time the unpleasant will not be 
picked up. The unpleasantness of the result serves to pre- 
vent the pecking response, although the immediate effect 
is to reject the food. The t-erms ' pleasant ' and ' unpleasant ' 
are probably the mental accompaniments of the benefit 
and injury which are instinctively appreciated. 

This trial and error process, then, is made possible by the 



2i8 FUNDAMENTALS OF PSYCHOLOGY 

numerous potential connections in the nervous system be- 
tween sensory and motor neurones. It is checked and con- 
trolled by the instinctive awareness of benefit and injury 
which is revealed in the pleasantness and unpleasantness 
of the results of stimulation and of action. All action is a 
resultant of these two processes: chance trial and control 
by instinct. 

The division of actions into two distinct parts, a more 
or less uncontrolled evocation of the process through chance 
connections on the one hand, and a control or selection by 
consciousness of what is suggested, on the other, is typical, 
we shall find, of mental processes as well as of physical. 
Whether we be thinking, or recalling, or imagining, we 
usually have a rather uncontrolled and irregular series of 
trials first, and then gradually hit upon some movement 
which is approved and accepted. We must always dis- 
tinguish between the arousal and the acceptance or rejection 
of any process, be it motor or sensory. 

REFERENCES 

Terman: The Measurement of Intelligence. 

Yerkes and Yoakum: The Army Mental Tests. 

Wood: Heredity in Royalty. 

Galton: Hereditary Genius. 

Pearson: The Inheritance of Mental and Moral Characters. 
Biometrika, 1904, page 131. 

Webb: Intelligence and Character. British Journal of Psy- 
chology, Monograph Supplements, Vol. I, No. 3. 



CHAPTER VII 
INSTINCT 

We come now to consider the second form of innate 
tendencies or capacities which determine the responses and 
finally the character of the individual. These are the in- 
stincts. As opposed to intelHgence and the general emo- 
tional and voluntary characteristics, which are merely 
capacities for larger groups of responses, instincts are either 
specific responses or tendencies that control the character 
of the specific responses. They may also be opposed to the 
above mentioned group, they are the endowment of the 
race as a whole rather than of any family or individual. 
They give unity to the race, since all men share in the in- 
stincts, while intelHgence and temperament serve rather to 
emphasize the differences of individuals. 

The term ' instinct ' is used to designate a large number of 
different processes, activities and tendencies to activities. 
So general has been the use of the word, in fact, that some 
writers desire to give it up as too vague. However, so many 
important facts may be grouped under the term, and the 
series of activities it describes is so important, that it seems 
much better to retain the word and to state clearly just 
what it is and what it is not to mean. 

The Nature of Instinct 

Definitions of Instinct. — Two distinct meanings of the 
word instinct are current. The first defines instinct as a 

movement or series of movements evoked by a particular 

219 



220 FUNDAMENTALS OF PSYCHOLOGY 

stimulus. The second defines it in a way to make it little 
different from the learning by trial and error mentioned in 
the last chapter. It is constituted by a series of tentative 
movements guided to an end by the pleasures that attach 
to possession, or the discomfort that results from lack of 
the object or condition that constitutes the end. Here the 
movements are not prescribed, in fact, vary greatly from 
situation to situation. What is instinctive is the pleasure 
or displeasure which impels to movement and assures the 
attainment of the end. 

The first is used to designate a more complicated re- 
flex. Thus, the pecking at a grain of corn by a newly 
hatched chick, and the complicated series of movements 
by which it breaks its way out of the shell, are instincts of 
the first type. An excellent illustration of the simple 
instinct dependent upon the stimulus and not modified to 
meet changing conditions is that of the solitary wasp 
noticed by Fabre, and quoted by Hobhouse as follows: ''A 
soKtary wasp, Sphex fla'vipennis , which provisions its nest 
with small grasshoppers, when it returns to the cell leaves 
the victim outside, and goes down for a moment to see that 
all is right. During her absence M. Fabre moved the 
grasshopper a Httle. Out came the Sphex, soon found her 
victim, dragged it to the mouth of the cell, and left it as 
before. Again and again M. Fabre moved the grasshopper, 
but every time the Sphex did the same thing, until M. Fabre 
was tired out." Instincts in this sense are more compli- 
cated than the reflex, involve a greater number of muscles, 
and a larger number of movements in a series. The Hne 
between reflexes and instincts thus defined is difficult to 
draw. Just how complicated a reflex must be to become an 
instinct is not easy to say. It has sometimes been asserted 
that instincts are more purposive, reflexes more mechanical, 



INSTINCT 221 

but even this distinction is not very clear, since most 
reflexes as well as instincts have a purpose even if reflexes 
are explained by mechanism. Again, there is always an 
impKcation in instinct that we are deahng with something 
that is or might be conscious, that is Kke voluntary action. 
But this is mostly an analogy, and, since instincts are very 
frequently not conscious, or we can only infer that they are 
conscious, even this criterion is not susceptible of accurate 
application. Instinct in this sense is a movement made in 
response to a stimulus or a group of stimuli as a result of 
inherited connections in the nervous system, a movement 
more complicated than a reflex, either in the number of 
stimuli that call it out, or in the number of muscles that are 
coordinated in its execution. In many minds, but subordi- 
nate to this distinction, is the further implication that the 
instinct is purposive, and more like voluntary or conscious 
movement than the reflex. 

Variation in Instinct. — As opposed to this rigidly deter- 
mined series of movements, most instincts show considera- 
ble variation and reach the final end by various ways. The 
hunting instinct of a cat, as exhibited in catching and killing 
mice or birds, adapts itself to the circumstances. Only the 
crouching as the prey is approached and perhaps the final 
spring are even approximately uniform. The cat usually 
plays with the mouse after it is caught, but even this is not 
a mere mechanical repetition of the same movement or 
series of movements. The resemblance between acts at 
different times is at best general. The reaction is to a 
number of separate stimuli each of which calls out a separate 
act, and the whole series is bound together by the general 
end. Probably, even here, each separate act is the result of 
a definite stimulus, but the connecting link that makes the 
whole a unit is found in the preparedness induced in 



222 FUNDAMENTALS OF PSYCHOLOGY 

the animal by one act which makes it more readily affected 
by a stimulus of the same group rather than by any other. 
The whole may be pictured as held together by an inherited 
tendency for the acts of the entire series to respond in suc- 
cession to definite sorts of stimuli. But there is much 
variety in the way in which the end is reached, due appar- 
ently to the fact that instead of preparing the way for one 
set of responses alone, a number of responses, eac*h of which 
may lead to the desired end, are rendered more* easy. 
Whenever a stimulus presents itself that excites any of the 
group of movements, the way is opened for carrying out all 
the others. 

Instincts as Ends. — Instinctive activities of the second 
class are still less definite in character. In the extreme in- 
stances of this class little is determined by inheritance 
other than that the desired end shall be attained. The 
attainment may be by any method that previous experience 
or the acquired habits shall dictate. The desire, not the 
movement, is instinctive. In this second class belong very 
many if not most of the complicated instincts manifested 
by the human adult. Acquisitiveness, combativeness, 
sympathy, and the great mass of instincts that may be 
regarded as protecting the human individual, the family, 
and the social group, are constituted of movements that 
have no regularity, but nevertheless drive the individual to 
a fairly definitely prescribed end. Thus, we speak of mating 
as an instinct, but the preliminary instinctive responses 
of coyness, and the whole series of courting activities, 
whether in the higher animals or in man, are indefinite. 
At the more reflex end of this class are movements that seem 
to be directed toward a definite end, but the separate 
responses are not each dependent upon the preceding act 
and the stimulus, but are complex mixtures of learned 



INSTINCT 223 

movements with a few reflexes. In simplest form the 
second class is different from the more general forms of the 
first only in the fact that movement and the stimulus are 
not so closely joined. One of several responses may be made 
to the stimulus. Again, one movement of the series does 
not follow so mechanically upon the preceding. Finally, 
the end is more in evidence. This end may be foreseen, 
although the reason for the dominance of that end or pur- 
pose is usually not appreciated. At the other extreme of 
this class, what is instinctive is the pleasure that accom- 
panies the attainment of the purpose rather than the con- 
catenation of movements that shall lead to that end. The 
acts made when one sees a beggar may vary from giving 
money to turning away as quickly as possible, but the feel- 
ing of pain that impels to some action is due to inherited 
causes. 

The term instinct, then, is used to indicate all acts whose 
conditions are inherited. It matters not whether those acts 
may be referred to specific inherited connections in the 
nervous system or whether the act is the result of striving 
for an end which some innate predisposition compels the 
individual to strive for, and whose attainment gives 
pleasure. While this definition is broader than that ex- 
plicitly given by many psychologists, all extend the term 
in practice to cover acts that belong only to our broadest 
class. At present most men incline to make instincts 
primarily reflexes of greater complexity, and to reduce as 
many as possible to the simpler forms of response. This is 
the more satisfactory, as it reduces to a minimum the nat- 
ural tendency to vagueness and the introduction of mystical 
forces. Even where instincts cannot be explained in this 
simplest way, there is no need to resort to the mystical, 
since the dispositions and preparatory irradiations may all 



2 24 FUNDAMENTALS OF PSYCHOLOGY 

be assumed to be due to the inheritance of specific disposi- 
tions in the nervous system, even if we cannot at present 
say exactly in what they consist. 

Specific Instincts 

Classification of Instincts. — The specific instincts are 
differently classified, and no complete agreement exists as 
to what shall be regarded as instinctive, even when the 
definitions have been settled. MacDougall limits instincts 
to flight, repulsion, curiosity, pugnacity, self-abasement, 
self-assertion, and the parental instinct (under which are 
placed care of the child, sympathy as an outgrowth of care 
for the offspring, and, by development, moral indignation). 
Minor instincts are reproduction, gregarious instincts, con- 
struction. Watson in his study of animals has eleven 
classes, — locomotion, obtaining food, shelter, rest, play, 
sleep, taken together as the basis for the daily and seasonal 
routine; sex, defence and attack, migration, mimicry, 
vocalization; and two less definite groups. It can be seen 
that almost all of MacDougall's list belong to our second 
class. Watson's are fairly evenly divided between the two. 
Some add more, others question some of these, but there is 
probably no chance of close agreement among all as to just 
how many groups there are, or even what specific acts shall 
be included in any group. 

It will be best to make a general classification with 
reference to the end that the act subserves, rather than to 
the speci'fic character of the particular instinct. One of 
the most convenient divides instincts into three classes: 

1 . Those which preserve the life and provide for the 
welfare of the individual; 

2. Those which provide for the continuance of the 
race and for the family; 



CLASSIFICATION OF INSTINCTS 225 

3. Those which make for the welfare of the tribe or 
of the social unit. 

Some of the acts belong to more than one class, — in 
fact, no one of the second or third would be possible without 
the first, — but the division is convenient in general and 
may serve as a guide through the maze. 

Individual Instincts. — Among the individual instincts 
we have those necessary for the care of the individual in 
the early stages of life. One of the best instances is found in 
the pecking its way out of its shell by the young bird. This 
instinct, according to Craig, is always carried out in very 
much the same way, although involving two important 
separate movements: pecking itself, and so turning in the 
shell that the shell may be broken in a continuous ring. 
Here, too, belong the first movements of taking food, which ' 
make their appearance almost at once, and change their 
character as the needs of the organism develop. Other 
individual instincts are involved in locomotion, walking, 
flying, or swimming, the care of the body in matters of 
cleanliness, the preening of the feathers by the bird, licking 
the body by cats, dogs, etc., the persistent hunt for para- 
sites that seems to occupy a large part of the spare time of 
all monkeys and apes, stalking game, fighting, flight from 
larger animals, in sum an imposing list. 

Instincts of Human Infancy. — In a recent careful study 
of several hundred infants in the maternity ward of The 
Johns Hopkins Hospital, Watson found that the number 
of instincts exhibited by infants up to 200 days was much 
smaller than is usually thought. He found only crying, 
nursing, grasping, movements of defence, eye-coordination, 
blinking, manipulation, and fears of falling and of loud 
sounds. The child from birth can support itself, will push 
away an object that injures it, and will feel about and inves- 



226 FUNDAMENTALS OF PSYCHOLOGY 

tigate any object that it can reach. On the other hand, 
Watson saw no evidence of instinctive swimming move- 
ments, of right-handedness, nor of withdrawal from filth. 
It is not claimed that some of the more complex instincts 
may not appear at later periods, but at the later period they 
would be mixed with learning and would probably belong in 
the class of instincts which are determined by the desirable- 
ness of the end, rather than of simple predetermined 
movements. It appears certain that the purely instinctive 
movements are relatively few in man. 

Fears. — The more liighly developed and complicated 
activities of the adult are many of them guided merely 
by the instinctive pleasantness of the end sought or the 
instinctive disagreeableness of the object avoided. This 
is true in large degree of the responses in fear, although 
some of the movements are fairly constant and common to 
many men. They show themselves in practically all men, 
although to be sure in different forms and in different 
degrees. In most cases they are not to be explained from 
experience, and many are absurd in the light of experience. 
Why a grown woman should be so startled by a mouse, why 
a man should make such exaggerated responses when a 
harmless snake wraps itself around his ankle, are hard to 
understand in the light of experience alone. Similar are 
the trembling at looking over the edge of a precipice from 
behind a perfectly secure railing, the fear of the dark, of 
caves and strange places, of the dead, and hosts of others 
that the reader may supply from his own experience. In 
the development of a child, these fears come one after 
another and frequently disappear almost as suddenly as 
they appear. For a few weeks or months a child will be 
afraid of fur, then the fear disappears and fondness for it 
replaces the fear. A cat may suddenly become an object 



CLASSIFICATION OF INSTINCTS 227 

of terror, and later, without other experience of cats, may 
arouse all signs of pleasure. Thus, the early life may be a 
constant succession of fears that come apparently with the 
stages of development of the nervous system. Interesting, 
too, it is to note the tendency of those fears to become 
exaggerated in diseased conditions of the central nervous 
system. Here we find fear of open places that leads the 
victim to slink around the sides of parks rather than walk 
across them (agoraphobia), and also, the opposite tendency, 
to fear all closed places, to avoid rooms and narrow streets, 
and to feel at home only in the open (claustrophobia). 
These are but two of many morbid fears. 

Among the instincts that aid to make up the individual 
character by the amount they contribute to the sum total 
of his instincts are pugnacity, the tendency to accumulate, 
and curiosity. The degree of pugnacity is one of the most 
important individual characteristics. It varies from the 
extreme in a tendency to domineer over every one, through 
a moderate degree of self-assertion, to a minimum in the 
weakling who never asserts himself. The one man never 
admits that he is wrong, will never see that he is beaten, 
but fights on to the end. Tempered with proper discrimi- 
nation of what is worth fighting for, this constitutes one 
of the elements in all strong characters; untempered, it 
makes the quarrelsome bully. The man in whom it is 
badly developed is ready to give up with the first disappoint- 
ment, if he permits himself to get involved at all. Closely 
related, if not identical, are the qualities of courage and 
cowardice. The collecting instinct is not quite so clearly 
demonstrable as an instinct, but the piling up of hoards of 
all kinds beyond the probable or even the possible needs of 
an individual seems to demand an explanation other than 
habit or reason. The intense pleasure which comes with 



228 FUNDAMENTALS OF PSYCHOLOGY 

the large accumulation is indicative of other than acquired 
characteristics. 

Curiosity is a striking character in the attitude of the 
higher animals as well as of men. The dog, the cat in less 
degree, monkeys in the extreme, show a tendency to exam- 
ine all strange objects. From their acts one might argue 
that they were intent on understanding them. Certainly 
in man there is a pervading restlessness until all unfamiliar 
objects and movements have been examined and explained, 
— an instinct that shows itself early and persists with in- 
creasing intensity until well into old age. In its simple 
forms in the child or in the uncultivated it impels an investi- 
gation of all possible sources of danger and provides for the 
security of the individual. In its higher forms it may well 
be regarded as the source of very much of man's desire for 
knowledge and of the growth of science developed from it. 
Much of this knowledge is probably useless from the 
practical man's standpoint, and in any case the investiga- 
tions that lead to the discoveries are most frequently carried 
out for the sake of the knowledge itself, rather than from 
any intention of obtaining practical benefit. The back- 
ground and foundation of the individual's character are to 
be explained in large measure from the degree in which he 
possesses different instincts. They determine in some meas- 
ure what shall appeal to him and, in still larger measure, 
the amount of effort that he devotes to attaining the end 
that appeals. 

Race Instincts. — No less important in the adult life are 
the race instincts. The mating instincts give illustration 
both of the definite but comphcated response, and of the 
vaguer movements determined only as to their end, or even 
by the pleasure that comes from the attainment of a given 
purpose, with little control of the method of attainment. 



SOCIAL INSTINCTS 229 

The manner of the manifestations of the courting impulses 
is, in man, not at all a matter of conscious purpose. The 
display and boastfulness of the male on the one hand, or 
his bashfulness in the presence of a chosen member of the 
opposite sex, on the other, is in most cases not intentional, 
and cannot be prevented at will. The coyness of the maiden 
is equally removed from voluntary control. Even more 
widespread in their effect upon society are the activities 
and feehngs involved in the care of the young and in keeping 
together the family. In man these processes are largely 
indefinite. They are guided by the pleasure of the parent 
in the welfare of the child. Most of the actual movements 
are learned through education and developed by habit. 
Only the pleasure produced by the achievement of the end 
and by the presence of the child is really instinctive; the 
rest is habit. In the lower animals of course the instincts 
are much more definite, as in the building of the nest, in 
determining the kind of food that is given, and the way it 
shall be given. Even here, however, much is left to the 
control of circumstances, for the processes cannot be reduced 
to a mere chain of reflexes. In man the continuous asso- 
ciation and the care for the welfare of the members of the 
family constitute an important element in the development 
of unselfishness in general and of all the ideal elements in 
character. 

Social Instincts. — The widest group of instincts, the 
social, are least often expressed as definite responses on the 
level of reflexes, and most frequently are merely goals im- 
posed by feelings of pleasure or the reverse. The most 
primitive of the social instincts is simple gregariousness. 
This is shown in its purest form in the lower animals, but 
is not without its analogues in man. The bison or reindeer 
or the wolf, under certain circumstances, seems to feel 



230 FUNDAMENTALS OF PSYCHOLOGY 

pleasure in merely being with others of his species. The 
same instinct may be seen in men who feel pleasure in being 
in the crowd on a city street, even if there be no words 
spoken and no intercourse of any kind with the members 
of the crowd. One may be absolutely alone, even avoid 
conversation with his fellows, and at the same time feel 
pleasure at their presence, or at least feel a haunting and 
unconquerable loneliness when away in the wilderness or 
where his fellows are not to be found. Obviously this 
instinct finds no simple expression in action, but is due 
merely to the pleasant feeling of being with others or to 
the displeasure of being alone. The individual may and 
usually does definitely plan the movements that will take 
him to a place where people are hkely to be found, but the 
tendency to dwell fondly upon the idea is instinctive, as is 
also the restlessness that may persist without awareness of 
its cause until other human beings chance to come. 

More active is sympathy which compels us to suffer 
with those who suffer even if we are jealous of those who 
rejoice. It is this that makes for self-sacrifice in all of 
its forms in behalf of those beyond the immediate family; 
it prevents cruelty on our own part and enforces giving 
aid to those who suffer at the hands of others or as the 
result of natural forces. It can be seen in the gregarious 
animals who exert themselves and even suffer in behalf of 
the herd, as the male deer are said to form a circle about the 
females and the young and to risk their own lives in defence 
of the unit. This instinct may be justified teleologically, 
since the survival of the individual and especially of the 
race depends upon the survival of the larger group. In man 
the most striking feature of the instinct is the limitation put 
upon the group included in its manifestations. It may and 
has been regarded as an extension of the racial instinct, the 



SOCIAL INSTINCTS 231 

instinct to protect the young, but it includes, with a force 
that diminishes with its extension, an ever-widening group 
of individuals. The members of the particular social set 
stand next to the family, then the individuals of the same 
class. The further extensions may include the ever-widen- 
ing circle of political divisions, it may be drawn in some 
degree in terms of religious or party affiliations, — in fact, 
any common belief or common purpose may serve as the 
bond of union within which the instinct of sympathy may 
act. In these divisions any common ideal, particularly any 
common ideal that has opponents, may serve as the basis 
for the organization of a group within which the bonds of 
sympathy are effective against all outside it. 

Sympathy as Basis of Social Organization. — These dif- 
ferent lines of organization may cross in many ways. One's 
fellows in social position may be opponents in politics or 
religion, but the bonds of sympathy hold in one respect or 
within one group when the same individuals are separated 
in other respects. These groupings, with the consequent 
feelings, constitute the essential facts in any understanding of 
social organization. In the widest form, the instinct includes 
all individuals, and thus makes possible the highest develop- 
ment of civilization. Only in the actions called out toward 
members of the accepted social group is it possible to 
assert that we are deahng with an instinct. What shall 
constitute the group within which the instinct works is 
determined almost altogether by education and tradition. 
With mutual knowledge and increasing numbers of common 
interests the number of individuals that may be included 
in a social unity has grown beyond the bounds of any one 
country. But on the other hand, a widespread war will 
suddenly make rearrangements of this grouping, will put 
beyond the pale many individuals who have up to that 



232 FUNDAMENTALS OF PSYCHOLOGY 

moment been most intimate members of some common 
group. The strong bonds between the socialists of all 
nations that existed before the Great War were suddenly 
broken by it. Thus, while instinct determines the treat- 
ment of the members of the common unit, education and 
experience determine who shall constitute the members. 

Social Pressure. — Not sympathy only but a harsher 
set of repressing instincts also work within these social 
groups. The beginning of these is fear of strangers and the 
mass, which as bashfulness makes its appearance in early 
youth. This persists with varying periods of increase and 
decrease throughout life. This milder first form of fear as 
seen in bashfulness becomes in its more general expression 
the means of social discipline that makes possible action 
in the group. It can be seen first in the direct repressing 
influence of the group when physically present upon all but 
the leader, and on him it acts more strongly than he is willing 
to admit. One rises with fear, if at all, to protest against 
any action of a crowd. Unless experienced, a man shows 
many signs of fear as he addresses an unfamiliar, even if 
friendly, audience. The wider influence of the effects of 
this fear of social disapproval and pleasure in social ap- 
proval can be seen everywhere in social affairs, and in 
many fields which are not usually recognized as social. It 
is social pressure which gives vital force to most ideals, 
religious and moral; and which compels us to follow styles 
in thought as well as in dress. One feels uncomfortable 
when clad in last year's gown, as one does when admitting 
adherence to an unpopular political party or to a generally 
condemned social theory. This is the real social pressure 
which compels conformity in every field. As an active 
force it drives the individual in much of his effort to get 
ahead. It keeps the student attentive to an uninteresting 



SOCIAL INSTINCTS 233 

lesson and it impels the laborer or business man to long 
hours of labor that shall enable him and his family to keep 
up appearances in their own social set or in that to which 
they aspire. These influences hold the man to his accepted 
place, keep him to his allotted task in moments of weariness, 
prevent eccentric acts and remarks, are the forces that 
make society possible, even if in very many cases they make 
convention dominate originaUty. In the individual they 
serve as spurs to many of the activities with a more remote 
purpose; they give the ideal and unselfish aim an approxi- 
mation to equal standing with the material and the selfish. 

Instinct and Conduct 

Instinctive Conduct. — We may look to instinct for an 
explanation of many phases of conduct which we cannot 
understand from the immediate circumstances or the earlier 
education of the individual. Through his instincts he is 
spurred to the avoidance of dangers that he does not know, 
is impelled toward the attainment of rewards that he cannot 
anticipate. Where he recognizes the goal and the purpose 
of the act, he is impelled, through instinct, to bodily reac- 
tions that he does not understand and which have no 
apparent meaning for the act itself. He trembles, he weeps, 
he smiles and glows with warmth, adjusts his tones to the 
mournful or the exultant key, all, so far as he can see, with- 
out reason. The insect lays its eggs and provides for the 
nourishment and protection of its young which in many 
cases it is never to see. In man the acts necessary for the 
propagation of the species are with more knowledge of 
the purpose, but nevertheless many of the details of conduct 
in that connection can be given no explanation from expe- 
rience alone, and the strength of the impulses can be under- 
stood only from forces beyond experience, and often opposed 



234 FUNDAMENTALS OF PSYCHOLOGY 

to reason. Balancing these in many respects are the social 
instincts which enlarge the circle of objects of instinctive 
acts and make the individual sensitive to the demands of 
the community with its laws and traditions. 

Instinct and Learning. — It must be remembered 
throughout, that instincts never show themselves in isola- 
tion or in pure form. They are always mixed with the 
reflexes on the one side, and with habit and even with reason 
on the other. The distinction between reflex and instinct 
is hard to draw. Even when it has been decided that an 
activity belongs to the class of instincts, reflexes are always 
present to determine the execution of the individual acts. 
Almost if not quite all instinctive acts are also influenced by 
learning. Even so simple an act as the chick's pecking at a 
grain of corn is not performed the first time in full perfection 
and, in the more complicated processes, the instinctive 
and experiential factors can with difficulty be isolated. 
In one set of experiments the first attempts at pecking on 
the second day of the chick's life gave ten correct responses 
out of fifty. This increased to an average of a little less 
than forty by the seventh day, from which stage the progress 
was comparatively slow. While mere growth with age is 
important, practice is necessary in all cases, as is shown in 
experiments by Breed and Shepard. They kept chicks blind- 
folded for periods varying from birth up to five days and 
found that the number of correct reactions the first day of 
practice was no greater for the older than for the younger, 
but the older made more rapid progress. By the eighth day 
all were approximately on the same level, irrespective of the 
number of days of practice. In the more compHcated acts 
of the higher animals, instincts are stiU more dependent 
upon training and habit formation. Birds kept in isolation 
do not ordinarily develop the pecuhar song of their species, 



SOCIAL INSTINCTS 235 

but a new one. On the other hand, where young birds are 
kept exclusively with older birds of another species, they 
learn the song of that species within the limits of their own 
vocal capacity. Even the English sparrow will approximate 
the song of canaries if kept near them from birth. Heredity, 
it seems, provides nothing but the organs and the possibility 
of forming suitable connections, together with the tendency 
to use the vocal apparatus in any necessary way. All else 
is determined by the practice of the individual, guided by 
the sounds that are heard. 

Language Develops through Imitation. — In man, 
instinct is still more mixed with habit and all the more 
rational and voluntary processes. Language is not instinc- 
tive as a specific process. As in the bird, what is instinctive . 
is the organization that makes sounds possible, the instinct 
of making sounds, with no reference to the kind, and the 
desire for the approval of his fellows which makes a child 
desire to repeat the sounds. These together suffice to de- 
velop in the child the language of the people with whom it 
is thrown, by whom it is reared. Even the simplest instinc- 
tive acts are not performed at the first trial in their full 
perfection. Both practice and intelhgent guidance are 
needed before great accuracy is attained. Here learning is 
hard to separate from the natural growth of the individual. 
The sex instincts appear in full vigor only as the individual 
approaches maturity. Other instincts come in part at least 
through the growth of the nervous system; they unfold 
one by one as the corresponding growth takes place. Still, 
it must be insisted that practice plays a part in the develop- 
ment of many instincts in man as it does in the pecking of 
the chick mentioned above. Furthermore, if the instinct 
is not used when it makes its appearance, there is some evi- 
dence that it may fall into disuse and fail to exhibit itself 



236 FUNDAMENTALS OF PSYCHOLOGY 

later when occasion arises. Instinctive movements depend 
upon learning for their development, take on much of their 
specific form through practice, and, in some cases at least, 
disappear unless used. 

Imitation and Play. — Specific instances of the way in 
which instinct and learning cooperate can be well illus- 
trated by imitation and play, often spoken of as instincts. 
As a matter of actual observation we find that imitation 
in the Ufe of man and the higher animals is very important. 
However, it is not possible to say that imitation is an 
instinct. The variety of movements involved is too great 
to bring it under the head of a complicated reflex, and, so 
far as one may regard it as a search for a goal determined 
by the pleasure of the attainment of the goal, nothing more 
is needed to account for it than the general instinctive 
pleasure of social approval. Thus, when the child learns 
to speak, it may be said roughly to be through imitation, 
but analysis proves that the child has an instinct to make 
sounds of no particular character. When by chance these 
result in words, the parents recognize and repeat, and give 
evidences of pleasure that lead the child to attempt to say 
them again; or the child may himself be vaguely conscious 
of the similarity of the sounds he makes to words that he 
has heard and so be more interested in them than in the 
other sounds. In any case it is the instinctive pleasure in 
sounds from others of his kind, and the approval they give 
to his own efforts, that lead to the repetition of the sound 
once made. Imitation in older individuals of movements 
that are already known in their elements can also be traced 
to similar general instincts. 

Play as Instinctive Expression. — Play also is an expres- 
sion of many instincts rather than of a single one. The 
tendency to play can be looked upon as a result of the 



DEVELOPMENT OF INSTINCTS 237 

general tendency to action, to motor discharge. The char- 
acter of the discharge, the particular form of play indulged 
in, is determined in part by the environment and by the 
general social instincts, and in part by a host of particular 
instincts. Thus, playing with a doll is partly imitation of 
the mother, partly an early budding of the maternal instinct ; 
the hunting and fighting plays, the constructive plays, all 
forms of rivalry and competition, are but the exhibition of 
different instincts under make-beheve conditions, under 
circumstances assumed to exist for the sake of the play. 
At most, play is no single instinct but the expression of a 
host of instincts under the pressure of a general tendency 
to act. It is an outlet for a reserve of energy under the 
effects of stimulation. The value of play in developing 
capacities through practice in advance of the actual neces- 
sity is obvious. 

The Origin of Instinct 

The Rise of Instinct. — The origin of instinct is pri- 
marily a problem for the biologist. Instincts are nervous 
dispositions that have been developed in the different 
species and are then inherited. The way in which instincts 
might arise has attracted most attention, as the inheritance 
is largely taken for granted. The opposing general theories 
of evolution — the theory of acquired characters and the 
theory of natural selection — have been appUed to its 
explanation. For psychology either theory suffices. It 
would be easier to explain instinct as the inheritance of the 
tendency to make movements that have been repeatedly 
made by the ancestors, but a great many biologists are at 
present sceptical of the possibihty of such an inheritance 
(the inheritance of acquired characters), and psychology 
has no evidence of its own to offer in its favor. It is certain 



238 FUNDAMENTALS OF PSYCHOLOGY 

that no specific acts which have been developed in a high 
degree by the father exhibit themselves in the child; and 
when any particular capacity of the father can be detected 
in the child, it is doubtful whether it is not due to the inherit- 
ance of the father's innate characters, rather than inherit- 
ance of his training. Barring inheritance of acquired char- 
acters, instincts must be due to the selection of the individ- 
uals who chance to develop tendencies to responses favorable 
to survival. The cause of the change in the germ plasm that 
produces the favorable instinct is not at all determined. It 
may be due to some chemical action, as in some cases it has 
been shown to be induced by physical stimuli; but given 
the change, however it arises, it tends to persist in the later 
generations. All that the doctrine of natural selection 
asserts in addition is that those organisms which chance 
to develop tendencies to action favorable to their survival 
and to the continuance of the species will increase in num- 
bers, and those which fail to develop this tendency will die 
out and their instincts will die with them. As a result of 
this selection in the course of the ages and innumerable 
generations of individuals, we find man a being provided 
with many of the structures essential to his present method 
of living, as well as many that are left over from stages in 
which they may have been useful, but which are now at 
best not harmful. Similarly, selection has given a nervous 
system with connections and predispositions that are on 
the whole adequate to the direction of the bodily structures, 
although there are some, those at the basis of many of the 
fears, for example, that might easily be dispensed with. 

In conclusion, we must assume that a number of the most 
fundamental reactions and demands of the organism are 
present in it from birth and serve as a foundation for the 
superstructure of learning. In part these are specific acts 



DEVELOPMENT OF INSTINCTS 239 

or groups of acts, in part they make their effect felt as ends 
towards which the organism must struggle by whatever 
movements it may have at its disposal. There seems to 
be a possibility of making either the movements that are 
aroused through instinct, or the feeling that accompanies 
the movement, fundamental in the explanation of all in- 
stincts. In the one case, each situation would call out a 
definite response, and, where the obvious response was 
lacking, it could be assumed that it was still present in 
some obscured or unnoticed form. On the other hand, it 
might be assumed that it is the feeling which is instinctive, 
— the pleasure that accompanies the instinctively deter- 
mined proper end, and the unpleasantness or restlessness 
that persists until that end is attained. As has been seen, 
one theory would hold very satisfactorily for one type of 
instinct, the other just as satisfactorily for another. It 
seems more in harmony with the facts and, on the whole, 
to offer less difficulty for the theory, to assume that both 
the movement and the feeling are accompaniments or results 
of the single biological predisposition. At the lower level 
the movement, at the upper levels the end which asserts 
itself only because it is pleasant when attained, are the 
more frequent characteristics of the instinct. This leaves 
much to be explained, but it does permit the use of the word 
in the broad sense, implied if not expHcitly adopted, by 
modern psychologists. 

In instinct we find the source of most of the movements 
and many of the f eeHngs which we cannot explain by imme- 
diate stimuli or from the earlier experience of the individual. 
It not merely provides the germ which is later developed 
into the complicated movements, but also many of the 
strongest incentives that we have in connection with our 
most complex voluntary and rational life. If one ask why 



240 FUNDAMENTALS OF PSYCHOLOGY 

one is afraid of the dark, why the mysterious thrills, the 
answer can be given only in terms of instinct. Similarly, 
if one ask why acquiring wealth, or inventing a new 
machine, or discovering some new truth, should be of almost 
universal appeal, we can again reply only that they are 
instincts. If one seeks the reason for falHng in love, and for 
many of the actions, particularly of the thrills and blushings 
and tones peculiar to that state, one must look to instinct. 
Finally, and most important of all, the social instinct sup- 
pHes the desire to be popular, to seek the approval of com- 
panions, upon which depends the force of social convention, 
and which drives to work when individual need and indi- 
vidual instinct exhaust their impelling power. If this 
extreme statement would seem to make everything worth 
while only because of its instinctive appeal, it must be 
remembered that instinct is developed, modified, and even 
restrained through experience, and reduced to conventional 
type by social pressure, itself an expression of the social 
instinjct. Certain it is that very many of the phenomena in 
connection with feeling and action and particularly in 
emotion can be understood, if they are to be understood at 
all, only through instinct. 

REFERENCES 

McDougall: Social Psychology. 

Morgan: Habit and Instinct. 

Watson: Behaviour. 

Watson: Psychology from the Standpoint of a Behaviorist. 

James: Principles of Psychology, Vol. II, Chap. XXIV. 

Pillsbury: Psychology of Nationality, Chap. II. 



CHAPTER VIII 

RECALL, AND THE QUALITIES OF RECALLED 
EXPERIENCES 

Not all of the material of knowledge comes directly from 
the sense organs. Memory, imagination, and similar pro- 
cesses have an equal part in our mental life. From the 
objective point of view, behavior is controlled by the past 
as well as by the present stimuli. Provisionally we may re- 
call and use memories as if they were on the same level 
as sensations. We may think of them as composed of, 
definite pictures which return as wholes or are recom- 
pounded of elements derived from the senses. We must 
seek to determine their components, and to discover how 
they are retained, and the laws that govern their reappear- 
ance. The primary qualities are like sensations. No abso- 
lutely new qualities can be imagined. Speaking generally, 
the quahties of memory and imagination are the quahties 
of sensation. It is possible to go farther and assert that if 
one is to have in mind images of a given quaUty, one must 
at some time have had sensations of the corresponding 
quahty. Individuals blind from birth cannot imagine 
colors; even the color blind cannot picture the colors 
which they cannot see. The same holds for all other senses. 
This has led to the general acceptance in modern times of 
the statement that all images are derived primarily from 
sensations. This simplifies our discussion to an investiga- 
tion of how the original impressions are retained, how they 
may be rearoused as occasion demands, and how their 
qualities differ from those of the original. 

241 



242 FUNDAMENTALS OF PSYCHOLOGY 

Retention 

The Nature of Retention. — Before asking how memories 
are retained we must inquire where they are retained. Two 
possibilities have been suggested in the history of the 
science: one that they are retained in mind or as mental 
states, the other that they are held in the nervous system. 
The latter view is at present generally accepted. The 
theoretical objection to thinking of memories as retained in 
the form of mental states is that mental states are by defini- 
tion conscious, whereas actually there is no awareness of 
memories until they are revived. The individual cannot 
tell that he has a memory, until he tests it by trying to call 
up particular facts. On the positive side, the evidence 
that remembering is in some way dependent upon the nerv- 
ous system comes from pathology. Numerous cases present 
themselves in which loss of memory is one of the prominent 
symptoms, and these usually show, on examination of the 
brain, injuries of portions of the cortex. Destruction of the 
area corresponding to a sense brings with it loss of the 
corresponding memories; destruction of neighboring areas 
or of paths of connection with other portions of the cortex 
also destroys or impairs the effectiveness of recall of the 
images. Studies in mental pathology have convinced 
psychologists that memory processes are closely dependent 
upon the nervous system. 

The methods of retaining memories offer more room for 
discussion. Various theories have been suggested, from 
the crude theory of the Greeks that memories were im- 
printed on the brain or soul, as the impression of the seal 
upon wax, to the scarcely less crude anatomical theory that 
each idea has a cell in the brain in which it may be stored. 
At present the tendency is to find analogies that shall be 



RETENTION 243 

within the known possibilities of the nervous system, and 
not to make the explanation more specific than the known 
facts warrant. The explanation is usually in terms of func- 
tion, of what the nervous system does when it remembers, 
rather than of the manner in which it holds the memories. 
Hering was among the first of the modern writers to suggest 
this method of approach, in stating that memory is a univer- 
sal property of matter. Any change that may be suffered 
by any substance tends to persist. Garments wrinkle where 
they have been often creased; for example, the folding is 
' remembered ' by the garment. Scars on the skin, even 
nail holes in boards, are memories, according to Hering, 
effects left on the substance by changes it has undergone. 
In the organic world similar facts are particularly striking. 
The physician constantly finds that any injury or disease 
of a tissue leaves an effect, — it is weakened for a con- 
siderable time. On the other side, exercise of a muscle 
strengthens it. 

Retention and Habit. — Habit is the best known expres- 
sion of this fact in its relation to the nervous system-. As 
was said in Chapter VI, habit may be defined in its most 
general form as a change induced in a tissue as a result of 
some act. This leaves a tendency to do that same thing 
more easily. Signs of habit formation may be seen even in 
the unicellular organisms. A Stentor responds differently 
after a series of responses have failed to give a pleasant 
result; and after the new variation has been repeated sev- 
eral times, it tends to persist for some time, too, — becomes 
a habit. In the higher organisms one may think of both 
habit formation and of memory as due to persistence of 
changes wrought in the nervous system by its action. 
Habits are regarded as due to changes in the synapses of the 
nervous system. Neurones that have acted together once, 



244 FUNDAMENTALS OF PSYCHOLOGY 

tend to act together again; nervous impulses spread from 
the one first active to the others, owing to the lessened 
resistance of the synapses that intervene. From the stand- 
point of Hering, memory in its essentials has the same basis. 
It is primarily the capacity of retaining the effects of one 
action of the nervous system in a form that shall make 
probable its repetition at some time in the future, rather 
than the retaining of some static thing, or impression, or 
idea. Speaking generally, after an object has once been 
perceived, a tendency persists for the neurones involved to 
act in the same way again, and this tendency leads to the 
revival of the image on suitable occasions. The nervous 
system may be regarded as acting in a certain way at the 
time of perception, and of repeating approximately the same 
action at some later time. Those portions of the cortex 
which are concerned, become connected as a unitary whole, 
and when one part is reexcited, the others are rearoused. 
What is left is merely the physical or chemical change in 
the neurones. Where this change takes place, can be deter- 
mined only by indirect means. Present evidence makes it 
probable that the most important part of the change is 
found in the sensory areas or in the immediately adjoining 
association areas, although no portion of the original 
nervous tract can be absolutely excluded from considera- 
tion. 

After-image, Memory After-image, and Memory Image. 
— One may also trace an analogy between memory and 
simpler forms of retention or prolongation of activity in 
the sense organ. In vision, gradations may be traced be- 
tween the after-image and the memory image. If one look 
for a moment at a bright color, the sensation will probably 
last for a fraction of a second after the impression has been 
removed. Even faint objects leave a second image, clearer 



RETENTION 245 

and of longer duration than the first, which does not move 
with the eyes, and may be shown to have its seat in the cor- 
tex. This process is known as the primary memory, and is 
probably partly identical with what Fechner called the 
memory after-image. It is sufficiently distinct to be used 
for all purposes in place of the actual sensation, and is for 
many purposes even more effective than the sensation. It 
may be regarded as due to a persistence of the activity of 
the cortical elements involved in sensation in just the same 
way that the after-image is a continuation of the action of 
the retinal elements. The cortical cells have even greater 
inertia and so act for a longer time than the rods and cones. 
A memory, on the same analogy, is merely the reinstate- 
ment of the primary memory image after the lapse of a 
longer or shorter period. The same nervous elements 
may be assumed to be active at the moment of recall as in 
the original stimulation, but they cease to act or at least 
cease to produce conscious processes for a longer or shorter 
time, and then the activity is in some way reinstated. The 
three — after-image, memory after-image, and memory 
image — all exhibit many of the same laws, and may be 
regarded as succeeding steps in the same series. The after- 
image is the persistence of the effect in the sense organ; 
the primary memory, a persistence of the activity of cells 
in the cortex; memory, a reinstatement of the activity in 
the cells of the cortex involved in the primary memory. 

Perseveration. — Granted the existence of a tendency to 
act again in a way once acted, it is next in order to ask how 
or when this reinstatement of the activity may take place. 
Two occasions are ordinarily recognized at present, — the 
perseverative tendency, and association. The former is 
simpler, although less frequent and less generally accepted. 
It was suggested by Miiller and Pilzecker that, when an 



246 FUNDAMENTALS OF PSYCHOLOGY 

impression has been made, the nerve cells impressed con- 
tinue active for a time, and in consequence, the correspond- 
ing ideas are likely to force their way into consciousness 
when nothing else offers, or to combine with other processes 
active at the same time in the production of more complex 
processes. This they call perseveration. Instances men- 
tioned are the reappearance of words that have been heard 
or spoken just before, but have no noticeable connection 
with the course of thought; the tendency of tunes to 'run 
in the head'; of complicated practical problems to keep 
returning to mind on all occasions, etc. This tendency 
seems to decrease rather quickly at first, but some slight 
effect apparently persists for hours, and when the original 
event is interesting or the impression strong, may last for 
several days. It is assumed that the activity of the nerve 
cells is continuous, but that the effect of their activity rises 
to consciousness only now and again. While the persevera- 
tion tendency itself is unquestioned, it is a matter of dispute 
how long it continues and whether the reappearance of the 
experiences after a little time are due to it, or to associations 
that have not been noticed. 

Association 

Laws of Association. — Association as an explanation of 
recall can be traced back to Aristotle in fairly accurate for- 
mulation, and approximations to it are found in still earlier 
writers.! jj^ Q^ie or another form it is recognized by all. In 

1 Closely related in meaning to association is the word suggestion. Sug- 
gestion, too, is used to designate the recall of one idea by another. Since, 
however, suggestion is also used for the evocation of a movement by an 
idea, and particularly because it has been applied very generally to the 
arousal of ideas and movements in h3^notism and similar more or less 
abnormal conditions, the psychologist usually avoids the use of the term in 
connection with the normal processes. 



ASSOCIATION 247 

general, this doctrine asserts that all reproduction of ideas 
is determined by the connections that have been formed 
at some time in the past. Conversely, mental processes 
which have once been in consciousness together, tend to 
return together. An empirical study of learning shows 
that words, nonsense syllables, or objects shown together 
or in immediate succession, tend to become connected and, 
when one is presented again, the other may also reappear. 
Learning the name of a new object, connecting a person 
with a place where he has been seen, all rote learning, are 
instances of this fact. On the physiological side, it may be 
said that all learning, all experience, is of things in their 
connections, and that all return is through the connections 
formed between neurones at the instant of learning. When , 
a group of neurones is active at the time of the original 
experience, paths of connection are formed, synapses are 
opened between them, and, later, when any element of the 
complex is aroused in any way, the impulse tends to spread 
over the partially open synapses to the other elements of 
the whole. Association has the same basis as habit, but 
need not end in a muscular response. As was said in the 
beginning of the chapter, all learning is Hke habit formation; 
all learning is dependent upon formation of connections 
between neurones, — nothing can be learned in isolation. 
In consequence, association is at once the fundamental 
fact in learning, in retention, and in recall. Learning is 
always the formation of connections between neurones; 
retention is always the persistence of the connection, or 
the partial openness of synapses which permits an impres- 
sion to pass from one to the other of the connected elements; 
recall is the rearousal of the whole complex by some one 
of the elements that may be stimulated from the outside 
world, directly or indirectly. 



248 FUNDAMENTALS OF PSYCHOLOGY 

While from the standpoint of learning it may be asserted 
with assurance that impressions presented together tend 
to return together, more complication appears when one 
attempts to determine what it is that brings any particular 
old experience to mind. Any idea that returns has almost 
always been associated with several, often with many, 
experiences; and it is difficult to say which one has been 
responsible for its recall. In fact, a number of factors more 
or less remote usually cooperate in the recall. Similarly, if 
some one familiar experience be presented, it is not possible 
to say with certainty what idea will be recalled by it. One 
may study the tendencies to recall, by presenting a number 
of words to a subject, and letting him speak the first word 
that comes to mind. If the same list of words be presented 
to a number of persons of approximately the same earlier 
experience, it is found that a large number of the responses 
will be common to all. Kent and Rosanoff secured the asso- 
ciations called out in a thousand people to each of one hun- 
dred words and found that the number of common words 
was very large. Thus to man^ 394 responded woman, 99 
male, 30 strength, 44 hoy, 30 person, etc. ; to mountain, 246 
responded high, 184 hill, 73 height, 90 valley; to soft, 365 
responded hard, 53 pillow, 34 easy, etc. If one will permit 
the train of ideas to wander uncontrolled for five seconds 
and then write down the ideas that present themselves, 
similar connections can be traced. The connections have 
from time immemorial been classified under four heads, — 
contiguity, succession, similarity, and contrast. In our 
list of words it will be seen that all the connections given 
can be traced to one of these groups. Soft and hard, moun- 
tain and valley, man and woman, may be regarded as con- 
trasting; hill and mountain, soft and easy, man and male, 
may be regarded as similar; soft and pillow, high and 



ASSOCIATION 249 

mountain, man and strength, as connected through verbal 
succession or by contiguity of the objects. 

It should be noted that this is a classification of the con- 
nections after they have been formed, and is made after 
rather than before the fact. It is a classification of the rela- 
tion the ideas hold to each other, rather than a statement 
of the causes of recall. Even so far as it holds, it is not 
altogether unambiguous. Mountain and valley are con- 
tiguous as well as contrasting, man and woman, as all 
contrasting things must be, are in some degree similar; they 
also are frequently found together and the words have been 
repeated in succession. For the real cause of arousal, we 
must turn again to the neurones that are involved in the 
activity. 

The Nervous Basis of Association. — A new method of 
forming connections in the nervous system seems to be 
implied in the association process. Hitherto, all of the 
connections studied have run from the sensory to the motor 
neurones; and the synapses that open are those that are 
traversed by the impulse. In association the connection 
is formed between two groups of sensory neurones and be- 
tween groups of neurones not on a single sensori-motor arc. 
Thus when a child is shown an object and hears the name 
spoken, the sight of the object excites a region in the occipi- 
tal lobe; the name heard arouses the auditory area in the 
temporal lobe. These areas are widely separated on the 
cortex, yet nevertheless after frequent recurrence of the 
excitations, a connection is formed between them of such 
a character that when the object is seen the name is thought, 
and when the name is heard the image of the object is 
reinstated. Two theories have been held to explain the 
way in which the path is formed. One is that the path is 
estabhshed indirectly through some common pathway of 



250 FUNDAMENTALS OF PSYCHOLOGY 

motor discharge. It is implied that the sound heard would 
lead to an attempt to repeat it, and the object seen would 
lead to the same response, and that all that would be needed 
would be to cross-connect the two sensory areas. This, it 
might be argued, again could be established indirectly by 
a backward opening of the path from the motor response to 
the sensory stimulus not previously evoking it. 

Association as Conditioned Reflex. — This form of asso- 
ciation is what Watson has called the conditioned reflex on 
the motor side. It is well typified in the dog which produces 
a salivary secretion, — ordinarily induced by the sight of 
food, — in response to the sound of a bell that has been 
frequently sounded at the same time that the food is seen. 
Similarly when a child is shown a cat at a time when it is 
indifferent to cats and at the same time a bell is sounded 
loudly enough to startle it, the withdrawal that comes 
with the bell is gradually transferred to the cat. Three 
objections may be raised to the assumption that the 
motor response is at all necessary to the formation of the 
connection. In the first place, the two motor discharges 
ordinarily run towards the same outlet, but with no lines 
of communication between them. In the second place, to 
assume that the path is formed along the lines of motor 
discharge means that the impulse runs from motor to sen- 
sory neurones. In the third place, connections of this cross 
character are formed when no noticeable movement results. 
These considerations make it necessary to assume that both 
for motor cross connections and sensory associations direct 
paths must be opened by the simultaneous activity of parts 
of the nervous system. 

The Law of Drainage. — The general assumption is that 
any two regions active at the same time either as parts of 
two sensory excitations or of two sensori-motor pathways 



ASSOCIATION 251 

tend to have paths opened between them. This is what 
McDougall called the 'law of drainage,' for he argued that 
whenever two parts of the cortex are active at the same 
time or in immediate succession the neural excitation of 
one tends to drain over into the other. This term 'drainage' 
is perhaps an inadequate picture, as the nervous discharge 
is very sudden, although there is the long-drawn-out-after 
effect of perseveration, during which something like drain- 
age may go on. However it be imaged, there can be no 
doubt of the fact that simultaneous activity of two parts 
of the cortex opens a path between them of such a character 
that whenever the one is aroused at a later time the other 
also tends to be aroused. The more frequent the repetition 
of this common excitation, particularly when the excitation 
later spreads by association from one to the other, the 
stronger is the tendency for one to arouse the other. 

One fact that limits the generality of this statement is 
that not all elements that are active simultaneously become 
so closely connected that one actually will recall the other. 
Only those elements which for some reason have something 
in common seem to be firmly united. Those that are at- 
tended to together, those which lead to a single act, those 
which are particularly intense or are accompanied by a 
strong emotion are strongly associated. Of these cases, the 
only one that would give any evidence of the occasion for 
selecting one element rather than another in forming an 
association is that they lead to a common act. This as 
stated above is not really a cause, since they lead to the 
common act as a result of their association, rather than 
becoming united because they both excite the same move- 
ment. At present then we can go no farther in our explana- 
tion of how these neurones become associated than to 
assert that when two groups of neurones in any part of the 



252 FUNDAMENTALS OF PSYCHOLOGY 

cortex are strongly excited at the same time or in close 
succession, a path is opened between them, and thereafter 
whenever one is excited the other tends to be excited also. 

Physiological Classification of Association. — The cause 
of the permeability of the synapses may be made the corre- 
late of either contiguity or of succession. The former is 
the simpler, as it is an expression of the law that two ele- 
ments active together once, tend to act together from that 
time on. Succession has practically the same explanation. 
The second neurone begins to act before the first ceases its 
activity, and so the two actions of the neurones are simul- 
taneous. If similarity is to be explained in physiological 
terms, it must be reduced to partial identity. What one 
calls an idea is always complex and may be pictured as 
corresponding to the action of a number of neurones. In 
what is classified as association by similarity, a mass of 
neurones corresponding to the first idea are active, and as 
time goes on, parts of the group cease to be active. Only 
the one group that corresponds to the part of the idea most 
attended to at the moment persists in its activity; and 
from this, new neurones that correspond to the elements 
of the second idea are excited by virtue of their previous 
connections with the persisting portions of the first. On 
the side of consciousness, many 'ideas' in the popular use 
of the term are complexes of experiences, complexes of 
sensations; probably also the action of many different 
neurones is involved in their appearance. In the recall of 
any complex idea, these different elements probably enter 
into many different combinations, and the effective con- 
nections are between the elements, not between the larger 
masses. Thus when an idea recalls another similar one, the 
similarity is due to some common element, and this common 
element may be regarded as persisting from one idea to the 



ASSOCIATION 253 

other. In one idea, everything disappears except the ele- 
ments that are common; these persist and gather about 
them by association the other elements which with them 
may be regarded as constituting the new idea. When the 
ideas are classified afterwards, they are seen to be similar, 
the association is said to be by similarity, but the effective 
forces have been the waning of certain elements of the first 
idea and the excitation of others by those remaining. Asso- 
ciation by similarity is really through partial identity, and 
the identical element furnishes the bond of connection. 

The Limits of Association. — Not only must we limit 
the application of the doctrine of associations by the asser- 
tion that it is the neurones at the basis of the elements of 
ideas that are associated rather than the ideas themselves, 
but we must also recognize that associations give only the 
possibility of recall, and that selection from the possible 
associates must be made by more remote factors. Most 
neurones or sensory elements have been connected at differ- 
ent times with several other elements, and may be regarded 
as having a tendency, whenever any one is aroused in any 
way, to rearouse each of the others with which it has been 
connected. Which of the possible elements shall be aroused 
is determined by the same elements that control attention. 
A discussion of these may be postponed to the next chapter. 
For the present we may say that the return of an experience 
or the renewal of an excitation of a group of neurones 
depends in some degree upon the continued activity (per- 
severation) of the elements in question, an activity that 
lasts for a relatively short time, but for the most part 
depends upon the fact that when any two groups of nerve 
cells have been active together at any time and one is 
reexcited, that excitation tends to rearouse its earher 
associates. 



254 FUNDAMENTALS OF PSYCHOLOGY 

Images, or Centrally Aroused Sensations 

The Qualities of Centrally Aroused Sensations. — These 
memory processes may be studied, not merely to deter- 
mine the ways in which they are retained and the laws of 
their revival, but also with reference to the actual content 
that they offer. One may study the materials of the remem- 
bered impressions just as one may study the quaHties that 
are derived from the external senses to determine the ele- 
ments that make them up or, more profitably, to com- 
pare them with the qualities of the immediate sensa- 
tions. 

Most untrained individuals do not notice the content of 
their minds as they recall; they are content to know that 
they recall an object and can describe it. Others who have 
had training in introspection find that they do not have 
images; they have no definite mental content when they 
recall an object but have merely the certainty that they 
have seen it before. Our present problem is to determine 
what is in mind when the object is recalled. If one is 
attempting to recall a desert or a mountain landscape seen 
years ago, for example, one may either repeat words that 
have been associated with the experience without any 
definite picture of the landscape, one may have fleeting bits 
of yellow sand or snow-covered peaks with many vacant 
areas or dark gray regions with no definite pictures, or one 
may have a clear and distinct picture from which one may 
paint or describe many if not all of the details. Our ques- 
tion at present is how these images differ from individual 
to individual, and how they resemble, and how they differ 
from, actual sensations. 

Two methods of investigation have been applied to the 
solution of this problem. The first of these was used by 



CENTRALLY AROUSED SENSATIONS 255 

Kiilpe^ in an experiment to determine how one might dis- 
tinguish faint sensations from imagined or remembered 
experiences. Faint sensations were chosen because mem- 
ories are generally beheved to be fainter than sensa- 
tions. Investigators were placed in a dark room where 
faint lights of different colors could be thrown upon the 
wall. At a given signal, the observers were asked to say 
whether a Hght was seen and then, if it were seen, to say 
whether it was objective or merely imagined. At times a 
Hght was really shown, at others not. In most cases at the 
signal the observers either saw or imagined a color. After 
the report had been given, an attempt was made to deter- 
mine what differences were used as a basis of deciding 
whether the image was really seen or only imagined. In 
this, observers varied. All agreed that there was a constant 
difference in quahty. The imagined colors were more 
transparent, were net-Hke or clouded. The sensations 
seemed brighter, they entered and left consciousness sud- 
denly and as wholes, had a more definite form, were clearer, 
and were given a more definite position in space. They 
were distinguished also by the more active tests, — that 
sensory colors left an after-image, were stationary when 
the eyes moved and vanished on closing the eyes, — while 
the reverse held in each particular for the imagined pro- 
cesses. In addition there were individual pecuHarities from 
man to man; for example, greater duration was given by one 
as characteristic of sensation and by another as character- 
istic of the image. The results of this investigation indicate 
that characteristically different quahties attach to the pro- 
cesses aroused through association which distinguishes them 
from the real sensations. 

The Projection of the Memory Image. — Another in- 
^ Kiilpe, Philosophische Studien, vol. 19, pp. 508-556. 



256 FUNDAMENTALS OF PSYCHOLOGY 

vestigation gives approximately the same results by a 
method even more striking. Miss Martin^ found that it 
was possible after a Httle practice to project a memory 
image outward into space, where it might be more readily 
compared with sensations. The different location of images 
and sensations serves in our ordinary experience as one 
criterion for distinguishing them. We refer perceptions 
to the point where the object is assumed to be in the outside 
world, while the memory or imagination either is given an 
indefinite place, is projected backward within the head, 
or possibly referred to the place where it actually is, but 
usually is not seen upon the surface that is actually pre- 
sented to the eyes. Miss Martin's observers found it pos- 
sible to bring the image and the object side by side. When 
the difference in projection that ordinarily exists between 
images and perceptions had thus been removed, it was 
found that there were still characteristic differences between 
the two in their coloring, in definiteness of contours, in 
clearness, intensity, and stability. The sensations had the 
advantage in each of these respects. One other character- 
istic is the relation to the movements of the eyes. While in 
these experiments the images did not always move with the 
eyes, there was always a tendency to movement when the 
eyes moved that could be avoided only by considerable 
strain. All of these criteria for distinguishing between the 
two agree with those indicated by Kiilpe's investigation. 
One other presents itself for certain observers, — that is, the 
tendency to see the images in front of the background of 
sensory objects which may be present. The background 
may be seen through them as through a veil. In general 
it is noticed that sensory impressions interfere with the 

1 Martin, Die Projektionsmethode und die Lokalisation visueller und 
anderer Vorstellungsbilder. 



CENTRALLY AROUSED SENSATIONS 257 

perception of other objects, while images do not thus inter- 
fere. 

Individuals who possess definite images, then, have also 
characteristic means of distinguishing them from the 
sensations. The images are sufiiciently different from the 
sensory experiences to prevent one from being mistaken 
for the other. Individuals frequently fail to notice the 
characteristics that serve to distinguish images from sensa- 
tions. In fact, few make this distinction until it has been 
called to their attention ; but the differences serve to ascribe 
the process to the world of things if of one character, or to 
the world of memory and imagination if of another char- 
acter. In addition to these differences in the mental con- 
tent, the connections in which the experiences present 
themselves also play a part in determining whether an 
experience is objective or subjective. If the object or event 
follows naturally upon other events that are recognized as 
objective, if the sound of steps is heard outside, the bell 
rings, a servant answers, and a moment later a friend enters 
the room, there is no question of the objectivity of the 
experience. If, on the other hand, a letter in a familiar 
handwriting is seen and then an image of the friend who 
wrote the letter appears, there is no doubt that the image 
is subjective. One event fits into the world of things, the 
other into the world of memories, and in consequence the 
one is assigned to the one group, the other to the other. 
This placing of the mental process in terms of antecedent 
events and the setting is undoubtedly the most important 
of the factors that lead us to discriminate between the 
objective and the subjective. Again this operation is not 
noticed for itself. One knows at once that one sees an object 
in the one case and that one merely remembers it in the 
other. The method of remembering is no more noticed 



258 FUNDAMENTALS OF PSYCHOLOGY 

than is the method of perceiving. That it is necessary to 
make the distinction is seen from the fact that in halluci- 
nations and in dreams mistakes are made. The processes 
aroused by association alone are referred to the real world 
and are treated as objects. 

Imagery Types 

The Materials of Memory and Imagination. — One may 

in a degree and for most individuals parallel the sensations 
which are regarded as constituting the raw material of our 
external experiences by a series of images or centrally 
aroused sensations which constitute the materials out of 
which the things that appear in memory, imagination, and 
reason, are composed, 'the stuff of which dreams are made.' 
These are retained in the central nervous system and re- 
aroused by stimuli that have been connected with them in 
the past and by other ideas that have been experienced with 
them. It should be noted that the memory images are 
usually not so complete as the sense presentations, that 
even the clearest of them have large gaps due either to im- 
perfect attention at the time of perception or to lack of 
interest in some phase at the moment of recall. Also much 
of our memory and thinking is not in definite reproductions 
or constructions of the objects, but is very sketchy. It is 
very frequently in words or in some other sjnnbol that 
represents or means the thing rather than a reinstatement of 
the elements which actually constitute it. This must be 
considered in detail later on; it is mentioned now merely as 
indicating that our inner mental life is not to be described 
completely in terms of definite images. Even where cen- 
trally aroused sensations are most definite, the number of 
qualities is less than the number that may be found in 
immediate sensation. Of the hundreds of grays, the un- 



MEMORY TYPES 259 

practised man cannot recall more than a dozen. Relatively 
few elements in memory must be made to do duty for the 
vast number of sensation qualities. 

Memory Types. — In our discussion of the qualities of 
the centrally aroused processes, it must be noticed not only 
that the quality of the memory element is not the same as 
the quality of the thing represented, but the way in which 
anything is recalled differs greatly from individual to indi- 
vidual. We all think of the same things, but probably no 
two of us have in mind exactly the same images when we 
think of the object. The main differences in representing 
objects and events can be most readily stated in terms of 
the sense organ or the sense material that is emphasized 
or drawn upon by the individual. The students of mental 
disturbance, Charcot among the first, noticed that certain 
men would make predominant use of the visual memories, 
others of the motor, others again of the auditory. Still 
later Gal ton ^ made a careful examination of the way a 
number of individuals recalled the breakfast table, with 
the result that some were found who would merely recall 
the way the dishes and the people at the table looked, 
others could remember the sounds of words and the rattle 
of the utensils, still others could remember only how their 
own various movements felt as they were made. More 
rare were the individuals who could remember the odors 
and tastes of the food, and these memories were usually 
indistinct and subordinate. Galton also distinguished the 
verbal type, individuals who recalled everything in words, 
either as words seen, or words heard, or words as they 
would be felt in the vocal organs at the time they were 
uttered. In older individuals, particularly men of science 
and others who indulged much in abstract thought, the 
1 Galton, Inquiries into Human Faculties. 



26o FUNDAMENTALS OF PSYCHOLOGY 

verbal tended to predominate over the more concrete 
imagery. 

Galton or certain of his expositors give the impression 
that an individual is Hkely to have one type to the exclu- 
sion or at the expense of all others. Certain of the later 
writers have still more exaggerated this assertion of the 
mutual exclusiveness of types. Strieker, for instance, has 
argued that every one must be of the motor type, and fur- 
ther that the recall consists in nothing more than the rein- 
statement, in some slight degree, of the movements made 
on a large scale at the time of the original experience. He 
challenges any one to think the sound of o with closed lips, 
and regards failure to do so as proof of his contention that 
all thinking is in terms of a reinstatement of some move- 
ment. Most recent investigators, however, incHne to the 
view that, while imagery is much more restricted than 
sensation, most individuals have memories from more 
than one sense, many from two or more in approximately 
the same degree. These latter individuals will use the type 
of imagery most suited to the problem in hand. If, for ex- 
ample, one both paints and composes music, one would 
plan a picture in visual images and compose in musical 
tones. While one or more tjApes may be lacking in most 
individuals, and one or more be preferred, the sharp classi- 
fication into visual, auditory, etc., seems too rigid to har- 
monize with the facts. 

Verbal Imagery. — Two major forms of imagery may be 
distinguished, the verbal and the concrete. They are not 
mutually exclusive in any sense, as most individuals will 
use the verbal in more abstract thinking and in cases where 
they must describe the event and will use concrete images 
on other occasions. Words may be presented to one's self 
in three distinctly different ways. 



MEMORY TYPES 261 

First, by revived kinaesthetic impressions, the sen- 
sations that come from the vocal organs when the 
word is spoken are revived in memory. This may, 
in certain individuals and at times in all, take the 
form of the shght movements of the vocal organs that 
were mentioned by Strieker. 

Secondly, in revived auditory sensations of the words 
as they might be heard when spoken by one's self or 
another. 

It is also possible to recall the words as they would 
look on the printed page. This visual recall is not fre- 
quent as an antecedent of speech, but where one at- 
tempts to recall letters or figures it may predominate. 
It will also be used when one is hstening to a language 
more famihar in reading than in speech. 
Concrete Imagery. — In concrete imagery any one of the 
senses may predominate and several may be used simul- 
taneously. Professor Griffitts, in an unpubHshed study 
of the imagery of more than one hundred students, found 
that more than ninety per cent rehed mainly upon visual 
imagery. Next in order of importance were auditory and 
motor, with less than five per cent of each. Even these, 
for the most part, used vision when recalling concrete im- 
pressions, but made large use of verbal imagery. Only one 
man was found in one hundred and twelve cases who had 
no visual imagery. While there were only very few who 
were confined to one sense in recall, there were great dif- 
ferences in the degree of clearness of the different forms of 
sensory imagery. Some individuals recall and imagine 
events visually with almost the vividness of real objects. 
Others have very indefinite images, which suggest rather 
than reproduce events. There is a marked difference be- 
tween dominance and definiteness of imagery. Certain in- 



262 FUNDAMENTALS OF PSYCHOLOGY 

dividuals who use almost no imagery but visual, have less 
vivid visual images than others who are predominantly 
auditory or motor, and have only secondary visual mem- 
ories. Another indication that imagery is not exclusively 
of one sense is the fact that individuals with well-developed 
auditory imagery also are Hkely to have vivid visual im- 
agery. One cannot speak of types, as the older men did, 
with the implication that if one has a well-developed im- 
agery from one sense, one is Kkely to be defective in others. 
Rather, it is true that men differ in the sense that they 
use most frequently in memory and imagination and also 
differ in the vividness or effectiveness of the sense that is 
dominant. 

The Origin of Imagery Types. — The differences are 
probably due in part to heredity and in part to training. 
Evidence may be adduced by a few cases in favor of a 
hereditary predisposition. Dodge, who is almost alto- 
gether without auditory imagery, reports that his parents 
had the same lack. The inheritance of musical abihty, 
which in all probability depends upon the possession of 
auditory imagery, may also be cited as evidence of a heredi- 
tary tendency. On the other side, training has been shown 
in several individual cases to have exerted an influence in 
changing the memory type. Particularly with school chil- 
dren, it is found that they can be trained to considerable 
facihty in types of imagination in which they possess no 
natural skill. Even in adults long practice gives results in 
the development of new forms of imagery. A student who 
cannot spell because he cannot see the words in his mind's 
eye can by repeated effort bring himself to visualize the 
words, with some degree of improvement on the practical 
side. It does not follow, however, that spelling is abso- 
lutely dependent upon the possession of the visual type. 



MEMORY TYPES 263 

It seems, then, that both heredity and training may play a 
part in determining the mental type, — certainly training 
may change what is given by heredity. 

Synaesthesia. — A curious occasional phenomenon is the 
close connection in certain individuals between objects or 
sensations of different senses. Numerous cases have been 
recorded in which letters have colors closely connected 
with them in the mind of an individual: a may be pink, 
green, etc. Words also either have a color of their own, 
or take on the color of the letters that make them up. 
Several cases have been reported, too, in which musicians 
have colors aroused by certain tones or tone combinations, 
and these may seem to be essential components of the tone 
effects. Thus Myers reports that Scriabin, the Russian 
composer, had a different color for the different keys. The 
major keys of C, D, B, and F# have the colors of red, 
orange-yellow, blue, and violet, respectively, and the 
effects are so strong that he desired to have his compo- 
sitions rendered to the accompaniment of colored lights 
that should flood the hall from concealed lamps. In 
another striking case odors were associated with colors; in 
fact, were often only perceived through their color associa- 
tions. 

Two theories have been held to account for the phe- 
nomenon: one that the connections have been made 
through association, the other that it is fundamental and 
perhaps due to the fact that there is some common feel- 
ing or other element which serves to connect the two sen- 
sory components. The second theory, if true, must admit 
that individuals who possess this idiosyncrasy seldom agree 
as to the colors that shall be associated with a particular 
tone, although each person who has it feels that it 
is universal and necessary. The association theory is as 



264 FUNDAMENTALS OF PSYCHOLOGY 

yet equally unproven, although a few characteristic peculi- 
arities suggest that the connection of colors with letters or 
tones may be due to old habits. Thus in three sisters whom 
I investigated, one of the few correspondences was thatj 
was said to have a gritty brown color to all three, an obvi- 
ous connection with jug. How far heredity plays a part, 
how far there may be more fundamental common charac- 
teristics between the sensations connected, and how far the 
phenomenon may be merely the result of early associations 
is still largely a matter of conjecture. 

In brief, the qualities of memory and imagination are 
the same as the quahties of sensations, a little less numer- 
ous, with not quite the same distinctness, but with no new 
quahties added. These impressions are recalled through 
laws of association not so very different from the laws of 
habit, and are woven together in new patterns to give fea- 
tures of remembered events that suit the purpose of the 
moment, or to make new constructions of imagination or 
reason. As is to be seen in the next chapter, these con- 
structions are subordinate to more general control in the 
same degree and by the same laws as sensations. 

REFERENCES 

Galton: Inquiry into Human Faculty, pp. 56-149. Every- 
man's Library ed. 
Stricker: Studien iiber Sprachvorstellungen. 
Woodworth: Psychology, Ch. XVI. 
MacDougall: Primer of Physiological Psychology. 



CHAPTER IX 

ATTENTION 

So far we have been tracing the influences of the envi- 
ronment, of past experience, and of evolution and heredity, 
in determining the actions and the mental states of man. 
These provide the materials of mind and the basic ten- 
dencies of action. One other characteristic of conscious- 
ness and action must be discussed. This is the fact of se- 
lection which is known both popularly and by psycholo- 
gists as attention. The stimuli that affect the sense organs 
do not exert an influence directly proportional to their 
energy or to the frequency with which they have been re- 
peated. Certain stimuli will produce an effect at one time 
that they will not produce at another. A faint stimulus of 
a certain kind will have a greater effect than an intense 
stimulus of another kind. This difference can be seen both 
in the movements that are excited and by the fact that 
one will affect consciousness, the other not. This fact of 
selection must itself be given an explanation. We must 
determine the laws under which selection takes place and 
if possible trace the changes to their causes. 

The Nature of Attention 

The fact of attention is apparent to every one and at all 
times. As one looks out over a landscape, one feature after 
another is noticed; as one sits at the study table working, 
the noise of the street, and memories of all kinds, will from 
time to time intrude themselves and crowd out the page of 

265 



266 FUNDAMENTALS OF PSYCHOLOGY 

the book, even if the eyes still wander along the lines of 
print and all the other physical conditions of reading are 
unchanged. In both cases the mental content varies be- 
cause of changes within rather than without the body. We 
are conscious at any time of only a fraction of the things 
that might be observed. Many sensory experiences pass 
unnoticed unless we look for them particularly. The vast 
majority of objects presenting themselves to the eyes are 
not seen, and many of the sounds that fall upon the ear 
are not heard. Only the few that appeal to us at the 
moment are selected. 

Consciousness as a whole has been likened by Wundt to 
the field of vision. There is a point of clearest vision in 
the centre where the cones are very close together, and a 
gradually decreasing clearness as one passes outward to the 
circumference. The point of maximum attention corre- 
sponds to the fovea in the field of vision, the other regions 
of consciousness to the periphery. Attention may wander 
over the field of consciousness in much the same way that 
the eye wanders over the field of vision. The common 
characteristic of foveal vision and attention is the increased 
clearness that comes in both cases. As a result, contours 
and differences in intensity between parts are better dis- 
criminated. Temporal effects of attending to a sensation 
have been noted in hastening its entrance and in keeping 
it a Httle longer in consciousness. All these differences 
would increase the importance of the impression attended 
to as compared with one that is not attended to. 

Does Attention Increase the Intensity of Sensation? — 
What change does attention bring about in the content of 
consciousness? The answer is to be found in the observa- 
tion of one's own state as one attends, rather than in a 
verbal description. Certain it is that the object or event 



ATTENTION 267 

attended to becomes in every way more important for 
consciousness; it stands out above the others at the mo- 
ment, is also more likely to be remembered and to start 
new trains of thought. The character of the change can 
be given only by comparing it with other known changes 
and indicating the similarities and differences between 
them. In many respects it is like an increase in intensity. 
Increase in the intensity of a physical stimulus also make 
it more likely to affect consciousness, increases the prob- 
ability that it will be remembered, and quickens the reac- 
tion to it. That attention and increase in intensity are 
not identical is evident from the fact that we never mistake 
one for another. We never assume that a sound has actu- 
ally become louder when we have only turned attention to 
it. On the other hand, it is certain that the two changes 
have much the same practical effects; both attention and 
intensity make the experience more important for con- 
sciousness. Attention also produces an increased clearness 
of outline. In this respect it has an effect similar to that 
due to increased closeness of the nerve terminations. 

The Distribution of Clearness. — Much discussion has 
arisen in the last few years among the people who would 
make clearness the primary characteristic of the attentive 
consciousness, as to the way in which clearness is distrib- 
uted over the field of consciousness. Titchener regards 
clearness as one of the fundamental attributes of sensa- 
tion on the same level with quality or intensity. He first 
asserted that there are at any moment in consciousness 
but two degrees of clearness, — the centre upon which at- 
tention is fixed and the hazy background. This first state- 
ment was softened in large measure, however, by the ad- 
mission that there might be differences in clearness in both 
upper and lower levels, separated by a marked break in 



268 FUNDAMENTALS OF PSYCHOLOGY 

the degree of clearness between the two levels. Under the 
criticism of Wirth, who asserted that consciousness grades 
off gradually from the clearest point to the most obscure, 
Titchener renewed his investigation of the question, and' 
found that there was a difference between individuals in 
this respect, that certain people belonged to the two-level 
type, others had a number of different levels or even ap- 
proached the gradual passage from maximum to minimum 
clearness that Wundt had described as the universal type. 
Attention as Selection. — The process of selection re- 
quires less description, although in its ramifications it prob- 
ably takes more different forms and is a more important 
psychological fact than clearness. In part, selection re- 
sults in an increase in the clearness of the content, — an 
element obscure at one moment becomes clear at the next; 
in part, the process selected rises from complete obscurity 
to a dominating place in consciousness, a possible content 
is made actual at one stroke. We are concerned with it 
primarily in its latter form when a stimulus that has been 
present but ineffective, suddenly rises to a prominent place. 
In later discussions it will be seen that the fact of selection 
is of fundamental importance. Not only stimuli but also 
ideas are selected. Control of association is selection and 
through ideas we reach decisions and govern actions. It 
will be found, too, that many of the same principles and 
the same conditions are involved in the selection of these 
higher or more complicated processes, that are involved in 
the simpler operations with which we are dealing here. 

Motor Aspects of Attention 

Motor Concomitants of Attention. — If we turn from the 
function to the subordinate features of attention, we find 
that a characteristic quality is given the experience of at- 



MOTOR ASPECTS OF ATTENTION 269 

tending, both for the one attending and the observer, by 
accompanying movements. These are of varied sorts and 
degrees. Most important in practice are the actions in- 
volved in the accommodation of the sense organs. As one 
attends, the organ adjusts itself to give the best possible 
conditions for observation. The eye at once turns so that 
the object falls upon the fovea, the lens without further 
thought is given the right curvature, the eye is in conse- 
quence focussed for the distance of the object, and the two 
eyes are converged to permit both to see it with the fovea. 
Each of these adjustments is made without specific inten- 
tion and usually without knowledge that they have been 
or are being made. One cannot contract the ciliary mus- 
cle to adjust the lens, by direct impulse. The only way to 
move the muscle is by attention to objects. If one attends 
to a distant object, the muscle relaxes; if one attends to a 
near object closely, it contracts, but this is the only way 
that it can be made to act. The same statement holds in 
less degree of turning and converging the eyes. The move- 
ment follows at once upon attention and is always a result 
of attending. In the other senses, the adjustments of the 
sense organs are less striking, although still present. The 
head is turned toward the source of sound to increase the 
certainty of receiving the tones. This is particularly no- 
ticeable if one ear be defective. The head will then be 
turned to one side when listening, to receive as much as 
possible of what is being said. The muscles in the middle 
ear probably have a protective function only, and play 
little part in attentive listening. When one is asked if one 
notices smoke, snifhng follows automatically to bring as 
much air as possible to and through the nostrils. Simi- 
larly, when a cook passes critical judgment upon a product 
of his art, the substance is pressed more closely against 



270 FUNDAMENTALS OF PSYCHOLOGY 

the tongue by bringing the tongue against the roof of the 
mouth. In feeHng a surface the hands are kept in motion, 
in order that the sHghter irregularities may be noticed. In 
the bUnd this frequently develops into a series of slight 
movements of the finger tips made automatically and al- 
most unconsciously. Comparing weights calls out similar 
lifting movements of the whole arm. Each sense, then, 
has a series of accommodatory movements that make the 
sensation more adequate and complete, movements that 
come without thought, are an immediate outcome of at- 
tending, of the desire to know more about the object in 
which one is interested. 

Mimetic Movements. — Another characteristic group of 
movements is carried out by the voluntary muscles of all 
parts of the body, which depend for their character upon 
the nature of the thing attended to. Every movement 
that is absorbing attention or that is watched attentively 
tends to induce or be accompanied by similar movements 
on the part of the onlooker. Thus if one is watching an 
athletic contest closely, it is probable that one will make 
sKght movements in imitation of the contestants. This 
tendency to act out ideas explains many of the cases of mind- 
reading and similar processes which approach the occult. 
SKght movements made without the knowledge or intention 
of the one and interpreted without the knowledge of the 
other serve as a basis for the communication. The capacity 
for interpreting these sHght unconscious movements is 
found in animals as well as in man. The feats of " Kluge 
Hans" and the Elberfeld horses, which seemed to do sums 
and perform other wonders, were found on closer examina- 
tion to depend in part upon noticing signals from the 
trainers which were given without the knowledge of the 
trainers. Thus a horse, when given a sum on the board, 



MOTOR ASPECTS OF ATTENTION 271 

would begin to stamp and continue the movements until 
the trainer indicated his satisfaction by some slight move- 
ment. These movements of the muscles of the face and of 
the bodily attitude constitute a large element in the appre- 
ciation of the mental attitude of a companion. 

Diffuse Motor Discharges. — Still another large group 
of movements of the voluntary muscles accompanying 
attention is constituted by a contraction of most of the 
muscles of the body, due to a general discharge of impulses, 
a sort of overflow of motor excitations. As one attends 
strongly to any object one becomes tense, the brow wrinkles, 
the teeth are set, the fists may be clenched. The degree of 
tension increases with the degree of attention. One uses 
the feelings of strain subjectively as a measure of the amount 
of attention, and one also regards the amount of contraction 
as a measure of the attention of another. It is not neces- 
sarily true that the efficiency of attention is measured accu- 
rately by the amount of contraction or of the resultant 
feehng of strain. These strains seem to be more pro- 
nounced when the resistance to be overcome is great, rather 
than when one is attending to the best advantage. But 
it is taken by the individual himself as an indication of the 
effort that he is exerting in attention, or of the effort that 
he is exerting in any field. Closely connected with these 
general contractions and accompanying marked attention 
is the inhibition of all movements. Some individuals must 
stop any movement they may be engaged in when they 
begin to attend, and in all there is checking of movements 
when attention becomes close. It can be noticed most 
clearly in an audience. When inattentive, there is always 
a sound made by the rustle of garments, by other move- 
ments, each in itself too shght to make a noticeable noise, 
but which in the sum produce a marked disturbance. As 



272 FUNDAMENTALS OF PSYCHOLOGY 

soon as the audience becomes attentive, all this stops and 
silence ensues. These inhibitions are of value in listening 
for faint sounds; and in many other sorts of attention they 
may increase the effectiveness of the sense in some degree. 
While necessary for audition, they have become an accom- 
paniment of all attending. 

Changes in non-voluntary physiological processes also 
are present. These are perhaps most strikingly seen in the 
checking of respiration. As one attends, the breathing is 
checked. In a short period of profound attention the breath 
will be held and a sigh or deep inspiration will follow relaxa- 
tion. In longer periods the breathing first becomes quick 
and shallow; in still longer periods it is slower, but also 
more shallow than usual. Similarly, there are changes in 
the circulation. The heart beats more quickly, the blood 
vessels contract in the periphery and expand in the brain, 
the blood pressure rises, the pupils are dilated, tears are 
secreted which give the bright eye of interest. Each of 
these movements renders the organism more efficient. 
Holding the breath removes the noises of respiration that 
might interfere with faint sounds. The quicker heart beat 
and increased circulation in the brain prepare for apprecia- 
tion of the conditions, and for the activity that may follow. 
Attention, then, is a physical as well as a mental process. 
Accompanying increased appreciation of some one sensation 
or stimulus is a widespread irradiation of impulses to the 
muscles. These serve to increase bodily capacity, are an 
indication to an onlooker of attending and of the direction 
of attention. The sensations of strain which come from the 
contractions are assumed to measure the degree of attention. 
Most so-called mental tension is physical, due to these mus- 
cular contractions. 



ATTENTION IS UNITARY 273 

Limits of Attention 

The Range of Attention. — One of the concrete problems 
that has been frequently discussed and most often measured 
in connection with attention is its range, the number of 
things that may be perceived at once. The experiments 
have been carried out by making very brief exposures of a 
number of* objects, and asking an observer how many have 
been seen. The exposure is limited to a fifth of a second or 
less, a time which does not permit any change of the atten- 
tion or movement of the eye. Results agree that four or 
five objects may be seen at a single exposure. It is interest- 
ing to note, too, that the number of objects that may be 
seen is relatively independent of the size or complexity of 
the object. One dot, a group of three or more that makes 
some regular figure, a letter, or a small word are all seen 
with approximately the same ease. In fact, a short word 
is more certain to be recognized than a single letter. What 
constitutes a single object is fundamentally that it has been 
used or treated as a single thing, rather than its physical 
complexity. The number of auditory impressions is sHghtly 
greater than the visual, but they must of course be given 
in succession. Eight single ticks of a metronome may be 
appreciated when heard without rhythm, and when com- 
bined in a rhythm as many as forty — five groups of eight 
each — can be heard in a single unit. The experiments also 
make it probable that the objects are not really seen all 
at once but that they are counted after the exposure in the 
immediate memory or memory after-image. Careful exami- 
nation of the process of attending to objects exposed for 
an instant shows that the real study of the object is made 
after the exposure. Impressions persist in the memory 
after-image with considerable vividness for some two 



274 FUNDAMENTALS OF PSYCHOLOGY 

seconds, long enough to count the five objects successively. 
One really attends, then, to but a single object at a time, 
but five successive acts of attention can be completed before 
the vivid memory image disappears. 

Much the same problem has been raised with reference 
to how many processes may be carried on at once. Occa- 
sionally one reads that some man is able to do two or more 
things at a time. Caesar was said to dictate to several 
secretaries at once, and similar tales are told of others. 
Experiments made to test the point all indicate that more 
than one process may be carried on at one time, but only 
provided some of them are sufficiently automatic to require 
no attention. Thus it is possible to write from dictation and 
add mentally at the same time, and the time required for 
doing both will be less than the sum of the times for doing 
each separately. If it is attempted to do three things 
simultaneously or to do two things even one of which has 
not become pretty thoroughly automatic, more time is 
required to accomplish them together than separately. Here 
again it seems that one can attend to but one thing at a 
time, although it is possible to start one series of activities 
and let it go on of itself while one attends to something 
else for a time. Attention changes from one to the 
other just often enough to keep the different processes 
going. 

The Duration of Attention. — Another question of similar 
character is how long one may attend without a break. 
This question has been given different answers at different 
times, and the answer depends in part upon what is meant 
by the question. Speaking roughly, one may attend to the 
same general subject, may read a book, for example, for an 
indefinite period. Careful observation of the course of 
attention to faint stimuH, however, shows that they will 



FLUCTUATIONS OF ATTENTION 275 

be appreciated only for short periods; they cease to be 
noticed in the intervals. Thus if one listen to the ticking of 
a watch or the faint tone of a telephone at a little distance, 
it will be observed that the sound will be heard for an instant 
and then will disappear, and these alternations will continue 
as long as one listens. Similar fluctuations are present dur- 
ing the observation of faint visual stimuli. The explanation 
of these fluctuations has been variously given as due to 
fatigue in the sense organs, either of the muscles or of the 
sensory endings, to fatigue of the sensory regions in the 
cortex, or to changes in the blood supply to the cortex, and 
even to fluctuations of mental energy. The explanation 
cannot be regarded as completely agreed upon, although 
considerable evidence has been given in favor of all but the 
last theory. What is probably more truly a fluctuation of 
attention is seen if one will keep a record of the time that 
one can fix upon some single, simple object, a dot or a single 
tone. It will be seen that the single object will dominate 
consciousness for only a second at the most, then something 
in the neighborhood will crowd out the first, or a memory of 
some event of the past will intrude to exclude it. Between 
each of the other events, attention will go back to the dot. 
The observer will be sure that the dot has been present all 
the time, but it will not have been attended to. It seems 
that one can attend strictly and definitely for a very short 
time, a second or so. In addition there are waves of in- 
creased effectiveness which come and go every six to ten 
seconds. These probably depend upon fluctuating physio- 
logical processes, central or peripheral. If by attending to 
the same thing is meant attending to a general subject that 
contains changing elements, it is possible to attend for 
several hours — the length of time depending upon the 
nature of the material, the strength of the observer, and 



276 FUNDAMENTALS OF PSYCHOLOGY 

other conditions. If, however, we mean attention to one 
thing exclusively one can attend only a second or less. 

Attention and Distraction. — It is very interesting to 
note that, on the whole, attempts to distract or to interfere 
with the attention of an individual usually result not in 
decreased, but in increased efhciency. Psychologically this 
was first noticed when attempts were made to measure 
attention by determining how much distraction was re- 
quired to prevent the observer from performing some pre- 
scribed task. Almost without exception, experiments of 
this type show an increase rather than the expected diminu- 
tion in efficiency during the distraction. A long investiga- 
tion by Morgan has given an indication of the reason for 
this result. Morgan had his observers make complicated 
calculations while records were kept of the breathing and 
of the pressure which was made in writing answers. The 
individuals undergoing the test would work undisturbed 
for a time, and then a phonograph would be started or other 
disturbing impressions introduced. The course of the work 
showed that there was in most cases an increase in the 
amount of work done. This increase would continue as 
long as the distraction lasted and the rate and accuracy of 
work would then decline below that which preceded the 
distraction. The explanation was found in a study of the 
records of physiological processes. In writing, pressure 
upon the paper increased at the moment of distraction, 
the respiration became labored and showed that the observer 
was aiding his work by shght movements of the vocal organs. 
All showed clearly that there was increased motor tension. 
This was an indication of increased nervous action, which 
was sufficient to augment capacity to a point which more 
than overcame the effect of the distraction, although at the 
expense of greater fatigue. One can parallel these results 



CONDITIONS OF ATTENTION 277 

in daily work. Occasionally, and in some individuals gen- 
erally, a disturbance will increase the capacity for work. 
The fact that the greater amount of work is at the expense 
of greater fatigue probably makes it undesirable to work in 
a disturbing noise unless necessary, but when necessary the 
increased accomplishment compensates for the discomfort. 

The Conditions of Attention 

Objective Conditions. — The underlying causes or con- 
ditions of attention are to be found in the antecedents of 
the attending process in the individual himself and in the 
material that offers itself from the outside world. On the 
one hand, the individual attends because he is at the 
moment or in general of such a character that he must 
attend to the particular thing at the particular time; on 
the other hand, the characteristics of some stimulus and 
the general nature of the environment are such that he 
cannot avoid noticing it. If one asks why any individual 
notices any particular thing at any particular time, one 
will find the answer either in the nature of the environment 
or of the individual. The objective conditions may be 
found in the attributes of the stimuh that are arousing the 
sense organs. The intensity, size, and duration of a stimulus 
and its contrast with the surroundings determine whether 
or not it is likely to be attended to. Loud sounds, bright 
lights, strong odors, force themselves upon consciousness; 
while less intense stimuli fail to attract notice. Contrast 
plays a part, as may be seen from the fact that a fairly 
bright light in the dark attracts as much attention as a 
brilliant light in full day light, or a light footstep in the 
silence of the night as much as the automobile horn in the 
midst of a dense street traffic. 

It is interesting to note in connection with objective 



278 FUNDAMENTALS OF PSYCHOLOGY 

factors that change is an essential element in arousing 
attention. One quickly becomes adapted to a continuous 
stimulus and ceases to notice it. A constant light is un- 
noticed, but the shadow cast by the passing of a cloud at 
once intrudes upon consciousness. The slight noise of the 
burning gas drops into the background, and as Fechner 
pointed out, the miller is oblivious to the sound of his mill, 
but the slightest change induced by a defect will be observed 
at once. The cessation of the stimulus in this case is as 
effective as an increase in the sound. A clock that has been 
ticking unnoticed in the study will be noticed when it stops 
and the last few ticks will be heard, — sounds that would 
have had no effect upon consciousness had they not ceased. 
The decrease in the size of an object moving directly away 
from us attracts attention almost as certainly as does the 
increase in size due to its approach. Each of these effects 
of objective stimuli might be explained as due to the univer- 
sal characteristics of man or to the inherited capacities of 
his nervous system. But since they are universal to all 
nervous systems it seems simpler to regard them as of objec- 
tive origin, than to assert that man's physical organism is 
adjusted through heredity to respond to stimuli possessing 
much energy and particularly to changes in the amount of 
energy affecting a sense organ. 

Subjective Conditions. — More truly characteristic of 
the attention processes are the subjective conditions. We 
ordinarily think of attention as a free act by which we turn 
to one thing which at the moment it pleases us to notice, 
and exclude all others. But frequently there is no conscious 
antecedent desire, and, where there is, the desires have their 
antecedents in the experience of the individual and these 
are to be regarded as the real conditions of his attending. 
Sometimes he knows that he desires to attend because of 



CONDITIONS OF ATTENTION 279 

the antecedent experiences; more often he first finds him- 
self attending and never knows why. If we examine the 
nature of attention in the hght of the history of the indi- 
vidual, we may distinguish five different groups of subjec- 
tive conditions. 

/. Immediately Preceding Sensations. — The first group 
of conditions refers to the immediately preceding sensa- 
tion. This can be best illustrated by hearing out overtones. 
If one is listening for an overtone in a note played on the 
piano, and has heard another note of the same pitch just 
before, he will distinguish it easily, while unless he has 
considerable training, he cannot hear it without this aid. 
So if one desires to hear the first overtone of c on the piano, 
and will strike c' just before he strikes the c, he will notice 
the overtone, the c' , without difficulty. Again an object 
just seen in a particular place will strike the eye when one 
seeks for it, where previously it would not have been 
noticed. Very much the same statements may be made of 
the idea in mind. If one can call up a definite image of 
what is to be seen, the corresponding object will be noticed. 
It is probable that the skill of the practiced observer in 
hearing overtones is due to the fact that he can recall 
accurately the tone that he is to hear. This definite image 
replaces the sensation in its effect of making the overtone 
likely to come into mind. Similarly, in a puzzle picture, to 
recall the concealed face in its actual place is a guarantee 
that the image will be recognized when one looks a second 
time. The image definitely recalled serves to aid the 
entrance of the corresponding percept, in the same way as 
does the immediately preceding sensation. 

//. Purpose or Mental Attitude. — Most important and 
striking of these subjective conditions is the influence of a 
factor that is variously designated the intention, the purpose, 



28o FUNDAMENTALS OF PSYCHOLOGY 

or the question in mind at the moment. When one has the 
intention of seeing a particular thing, that thing will come 
to consciousness. If some one suggests that you look for 
a cell in the field of a microscope, the probability that you 
will see it is thereby increased. In daily life this purpose is 
the determining factor in all observation. One usually sees 
or hears what one desires to see or hear, or what harmonizes 
with the intention. All that does not harmonize with that 
purpose, unless especially favored by objective conditions 
or other more general subjective conditions, might as well 
not have been offered to the senses. If one is interested in 
what an individual is saying, one will not notice his accent 
no matter how unusual, and if one is a phonetician and in- 
tent on the study of the peculiarities of speech, the meaning 
may be altogether lost. One does not notice the wall paper 
in a room unless the pattern is striking, or one is deciding on 
wall paper for one's self and so has that as a dominant pur- 
pose at the time. Some objects that have been under one's 
eyes for years may never have been noticed unless some 
purpose made it desirable. To use a familiar instance, the 
reader cannot say without looking whether the four on 
his watch is iv, 4, or iiii, in spite of the number of times it 
has been looked at. One looks to learn the time, not to 
see how the numerals are printed, and sees just what one 
looks for, and nothing else. This is typical of most observa- 
tion. Man is blind to what does not correspond to his 
momentary purpose. 

This purpose or mental attitude may be aroused, either 
from without or from within. From without it may be due 
to a question asked by another, or to some task that has 
been set, or problem that has been raised by one in au- 
thority. From within, the purpose usually arises by a sug- 
gestion from something that has been seen. Something 



CONDITIONS OF ATTENTION 



281 



external or internal starts a train of associations. That 
raises a question about an object present, and one looks to 
the object for an answer. The answer to the first question 
suggests another problem, and thus a train of associations 
in the series of questions leads to one observation after 
another. Observation is most frequently the result of a 
series of problems self-set for solution. When one has the 
problem or the question, finding the answer is relatively 
easy. Without the problem, observation is indiscriminate 
and relatively unprofitable. In this sense thought usually 
precedes observation, but the thought itself grows out of 
preceding observation, and so both are to be regarded as 
parts of a continuous progression in which each thought 
suggests attention, and the results of each attention, a new 
thought, in a succession broken finally by the irruption of 
an intense stimulus or the necessities of the daily Hfe, and 
this in turn starts a new series of questions. 

///. Education and Attention. — A number of more 
remote conditions also aid in preparing an individual to 
attend in a given way at any moment. First of these is the 
earHer training and previous experience. This works in 
two ways: in the first place, it increases capacity for obser- 
vation of the object one desires to know about, and it largely 
determines what one desires to see. The skill of experts in 
any sort of observation depends upon training. The skill 
of expert microscopists in any reahn, of musical critics, 
of tea and wine tasters, and of the woodsman in tracking 
game and in seeing the signs of the forest, all comes from 
training. The expertness depends in part upon knowing 
what to look for, of having in mind the problems that are 
to be solved in a particular connection; in part, the skill 
in discrimination grows with practice, and is probably 
dependent upon a number of physiological factors. Train- 



282 FUNDAMENTALS OF PSYCHOLOGY 

ing has also obvious effects in determining what sort of 
stimuli shall be selected for attention. This works in two 
ways. In the first place, it helps to raise questions, to organ- 
ize purposes. One cannot have a purpose without some pre- 
liminary knowledge of the thing to be seen. What to look 
for in animal structures is known in any considerable degree 
only by individuals with some training in zoology. The 
trained machinist has a series of questions in mind as he 
begins to examine the engine that you have called him to 
repair, and with these problems which have grown out of 
his experience he looks with a definite series of purposes and 
easily discovers the source of trouble. But, secondly, even 
with no definitely conscious purpose, one sees the things 
that one has been accustomed to deal with, or that one has 
been trained to see. The printer without effort sees details 
of a book that escape the ordinary reader. 

IV. Social Forces in Attention. — Still another important 
group of influences are the outgrowth of social instincts. 
These compel respect for the ideals that one takes from 
society, and make one strive to do and observe certain 
things because of the fact that others expect such behavior. 
The student attends to a lesson when fatigued or when the 
lesson is not interesting in itself because he desires to make 
a good record, to pass an examination. Or again, a man 
desires to make a good record for the sake of the approval 
it will win from persons he respects. Or selecting a more 
permanent aspect, one desires to obtain a satisfactory 
knowledge of a subject for the value it may have in later 
years, or in the profession that has been adopted. Again, 
however, choice of a profession depends largely upon the 
social favor that the profession has in the group with which 
one is acquainted. Even the belief that the particular 
subject will help in the profession is often taken from 



CONDITIONS OF ATTENTION 283 

society. It is a preference for the remote as opposed to the 
immediate good, but the more remote is accepted as good 
and obtains impelling force because of the influence of 
society. Society approves each separate step, as well as 
the attainment of the end; its pressure is felt throughout 
the whole course of the attainment, and thus at once guides 
and compels towards that end. For our present purpose 
it may be regarded as the source of all attention from 
constraint, of all attention against one's momentary 
desire. 

V. Heredity and Attention. — A final condition of atten- 
tion, most remote in time, is found in the hereditary dis- 
position. This heredity may be either immediate, as in the 
inheritance of individual traits, or distant, as in attention 
due to general instinct. The former is less easy to illustrate 
or to demonstrate, but it seems probable from special 
studies in attention and the more general studies in heredity, 
mentioned in Chapter V, that certain of the tastes of an 
individual, which are either derived from the natural direc- 
tion of his attention or control it in certain respects, are 
inherited from his parents. The more general heredity is 
seen in the fact that one attends to moving objects, to per- 
sonal combats, to all objects that are likely to be especially 
beneficial or injurious. In general, if one asks why one 
attends to anything at a particular time, the answer may 
be found in the nature of the external objects, or in the dif- 
ferent mental states at the moment, in the experience of 
the immediate or of the remote past, and finally in the 
inheritance of the individual. As has been pointed out, 
these cooperate in many ways and vary independently from 
moment to moment, but could we know the individual 
completely in all of his characteristics, his past history, and 
the influences working upon him from the environment, it 



284 FUNDAMENTALS OF PSYCHOLOGY 

would be possible to say fairly closely, even with our present 
knowledge, to what he would be likely to attend. 

Attention and Association 

Control of Association. — Selection is quite as important 
in controlling the course of the associations or in deter- 
mining the ideas that shall be recalled or suggested, as in 
choosing the sensations that enter consciousness. It is 
evident that the mere strength of connection between ideas 
would give only a rigid, mechanically determined series of 
thoughts with no flexibility or adaptation to varying con- 
ditions such as is required in logical thinking or purposeful 
imagination. This inadequacy of the associative connec- 
tions to explain the real course of thinking has led many 
to abandon the theory altogether, in spite of the fact that 
in some degree the importance of old relations in deter- 
mining what shall be recalled has been recognized all 
through the history of psychology. It seems more in har- 
mony with the facts to accept the view that fundamentally 
all recall goes back to association, that each impression re- 
called must be suggested by the preceding, but that since 
each idea has been connected with many others, there 
must be other conditions which have united to bring back 
just that idea and no other; or, viewing the process in 
advance of the recall, the arousal of one idea, connected 
with the thought in mind, rather than another depends 
upon a number of forces, which work together with the as- 
sociative tendency in determining the recall. 

The Goal Idea. — Two different theories, at present cur- 
rent, attempt to remedy this deficiency in the doctrine of 
association. One proposed by Aschaffenburg and much 
used by the psychiatrists would refer the determination of 
the course of ideas to the effect of the final idea in the 



ATTENTION AND IDEAS 285 

series, — the goal idea. Thus if the goal of the sentence 
is to describe the weather, one set of words will be sug- 
gested; if the aim is to decline an invitation, another series 
of words may be called out, even if one start with the 
same word. When the course of thought leads to the goal, 
it is said that the goal idea dominates it; if it wanders at 
random by virtue of the strength of the connections be- 
tween each pair of ideas, we have to do with another sort 
of thought. For the diagnosis of mental disease, thinking 
dominated by goal ideas is normal, while, when the goal 
idea is lacking or is of slight effect, one has an indication 
of mental abnormality. There can be no doubt that these 
terms describe an important difference between types of 
thought, that associations may be classified in this way. 
It is open to objection in that it gives merely a descriptive 
classification rather than an indication of the effective 
causes or conditions in the course of ideas. One cannot 
think of the last idea in the series as exerting an influence 
upon those that precede it. A force cannot be regarded 
as exerting an influence before it comes into being. 

Mechanical Factors in the Control of Association. — On 
the other theory the same facts are taken into considera- 
tion, but the explanation is in terms of determinants rather 
than of goals, of antecedent rather than of consequent 
events. We may take over almost bodily our conditions 
of attention and apply them to enumerate the factors that 
determine the selection of one possible associate from the 
others. Corresponding to the objective conditions, we find 
the factors that determine the strength of the connection 
between one element and those that have been associated 
with it. These have been shown to be the frequency with 
which the two elements have appeared together, the re- 
cency of their association, the degree in which they were 



286 FUNDAMENTALS OF PSYCHOLOGY 

attended to or the intensity of the stimuh that called out a 
response at the time of their earlier appearance, and the 
primacy of the association. Professor Calkins has shown 
that the earlier one element enters into an association with 
another, the more likely it is to be recalled with that than 
with any other with which it has been associated at a later 
period. It should be added that Galton found that very 
many of the ideas in a train came from youth. He kept a 
list of ideas that were suggested to him by objects or 
words, and then traced them to the time of their original 
experience. Thirty-nine per cent were found to come from 
boyhood and youth, 46 per cent from the period of 
subsequent manhood, and 15 per cent from quite re- 
cent events. This indicates that impressions received in 
youth are better retained and are stronger in their connec- 
tions than those received at later times. This may be said 
to be due, either to primacy, that is the greater degree of 
retentiveness of the associations first formed, or to the 
greater interest in the events of the early period of life. 
Professor Calkins also found that primacy was an impor- 
tant factor in the determination of the strength of asso- 
ciates, even when they were formed in adult life. 

Intensity and Recall. — A number of experiments from 
Ebbinghaus prove that both the frequency and recency of 
associations are important elements in the determination 
of the probability of recall. Intensity does not lend itself 
so well to experimentation, but chance observation indi- 
cates that the more intense stimulations leave more per- 
manent effects. Under this head come cases in which the 
intensity is of subjective origin, is due to a strong feeling 
or to close attention. It has been shown that the degree 
of attention increases the likelihood of recall, and, while 
the experimental case for feeling is not so complete, there 



ATTENTION AND IDEAS 287 

is good evidence from everyday life that this, too, serves to 
increase the closeness of the connection. As a result of 
these objective conditions, the tendency of any idea or par- 
tially aroused neurone to arouse some other is constant. 
Furthermore, were this strength of connection the only 
thing to be taken into consideration, it would be very dif- 
ficult for the connections to be changed. The idea recalled 
by any given idea would be determined once and for all. 
The only way one association could be broken and another 
substituted would be to permit a long lapse of time and 
the formation of some very strong new association. It 
would mean, in any mind subject to its rule, a perfect 
mechanism with no possibility of breaking away from its 
domination. 

Subjective Conditions of Recall. — This tyranny of as- 
sociation is tempered by the subjective conditions of atten- 
tion which play a part here, as well as in the entrance of 
sensations to consciousness. By far the most important of 
these is to be found in the mental attitude of the moment, 
the purpose or problem that is set the individual. If one 
be given such a word as dog, a very large number of asso- 
ciates can readily be recalled. If, however, it is coupled 
with the request to name the class to which it belongs, ver- 
tebrate, animal, or some other more general term will be 
aroused. While if one is asked to give a member of the 
class, a species of dog or the name pf some particular dog 
is spoken. There is still room for selection within the 
group, but the group itself is very much narrowed. Simi- 
larly, if two numbers are shown written one above the 

other and a line drawn beneath, as ., six, eighteen, or 
seventy-two might be associated with them. If they ap- 



288 FUNDAMENTALS OF PSYCHOLOGY 

pear in a check book or in other real relations, the purpose 
and the knowledge of what has gone before serve to deter- 
mine whether one or another number shall suggest itself. 
If the problem is set by another, if the sum appears in a 
series in which one has been asked to add, subtract, or 
multiply, that request will suffice to suggest the corre- 
sponding figure. In any case, either the task that has been 
set by another, the demands of the situation, or the atti- 
tude that one may happen to be in, will choose from among 
the possible associates the one most suitable. In addition 
to the setting, education and the social influences that are 
behind voluntary control of attention also have an impor- 
tant part in the guidance of ideas. While association pro- 
vides the possible paths along which ideas may flow, these 
possibiHties are made actualities by the more subjective 
conditions derived from the earUer experience and present 
intentions of the individual, and the necessities that bear 
upon him at the moment. All the factors that control at- 
tention serve also to select the associates. 

Forms or Attention 

Three Forms of Attention. — It is customary to di\dde 
attention, whether appHed to external objects or to the con- 
trol of ideas, into three groups, — voluntary, involuntary, 
and non- voluntary. In popular terms the basis of division is 
with reference to the presence or absence of the will. As 
we do not care to raise the question of the will at the pres- 
vint time, we can make the classification with reference to 
the conditions and characteristics of the attention process 
discussed above. 

Involuntary Attention. — In general, it can be seen that 
the attention called involuntary corresponds to attention 
that is determined altogether by the objective factors. We 



FORMS OF ATTENTION 289 

attend in spite of ourselves because the stimulus is strong 
enough to force itself into consciousness, whatever the 
state of consciousness itself may be at the moment. At- 
tending is against the will, against the desire of the indi- 
vidual at the moment. We desire to read, and the noises 
of the street force themselves upon us, or we desire to re- 
call the book in which a certain statement was made, and 
a large number of ideas keep forcing themselves upon us. 
In the latter case the associations of irrelevant things are 
so strong that the relevant idea is kept out. 

Voluntary AUention and Effort. — Voluntary attention, 
on the other hand, is that which is determined by social 
pressure. The desire to attend is not one that springs 
spontaneously, but is due to the impulsion of some remote 
end. In most cases, a struggle between the immediate and 
the remote good or pleasure is involved. Usually, too, as 
has been said, the remote good is impressed upon us by 
some form of social pressure. The approval of some part 
of the immediate social group is necessary to make the 
distant goal more attractive than the inherently pleasant 
processes that would lead us away from it. In this sense 
social pressure is the real motive force behind attention, 
the force that holds the individual to the less pleasant in 
the face of the more pleasant. The characteristic conscious 
accompaniment of voluntary attention is a mass of strain 
sensations, sensations which, taken together, constitute the 
feeling of effort. As was said in the discussion of the motor 
accompaniments of attention, all attention involving con- 
flict of motives tends to arouse diffuse contractions in a 
number of muscles, contractions which are in themselves 
of no great effect upon the attention process, but which 
are accepted as an indication that some force is active. 
They make us feel active, are said to constitute a sign of 



290 FUNDAMENTALS OF PSYCHOLOGY 

the activity of the will. So far as we now know, they are 
not a cause but an effect, they are a sign, not of a new 
force, but of a conflict of conditions. That they have no 
good effect is evident from the fact that they do not ac- 
company the most effective attention and, when they ap- 
pear, usually die away as soon as the highest stage of effi- 
ciency of attention is attained. Voluntary attention is due 
to social pressure and is accompanied by strain sensations. 
All strain sensations taken together constitute what we call 
the feeling of effort. 

Non-voluntary A Uention and Interest. — The non- vol- 
untary form of attention includes all classes not previously 
covered. The more important conditions are the mental 
attitude of the moment, the momentary purpose, educa- 
tion, and heredity or instinct. These seem to induce at- 
tention in accordance with the momentary nature of the 
individual; they constitute in sum total the conditions of 
desire. The characteristic accompaniment of this form of 
attention is interest, a feeling of pleasure due to the lack 
of conflict. In so far as it is strictly interest, it is a pleas- 
ure derived from the mere act of attending, rather than 
from the nature of the thing attended to. Why it should 
come or how it originates need not concern us here; in 
fact, no satisfactory explanation has been given for it. It 
is essential to emphasize that both interest and the feeling 
of effort are accompaniments or effects, not causes. After 
all, then, these three divisions of attention are not entirely 
distinct. All forms produce the same effects in conscious- 
ness; they are distinct only in that in certain cases the 
sensations of effort or the feeling of interest accompany 
them; they gradually shade over into each other without 
sharp line of division. Attention is a unitary process. 



PHYSIOLOGICAL THEORIES OF ATTENTION 291 

The Physiological Basis of Attention 

The Physiological Explanation of Attention. — On its 

physiological or nervous side, attention may best be pic- 
tured as a preparation of one tract or set of tracts for action. 
The nature of this preparation in advance of the entrance 
of an idea varies for the different subjective conditions. 
The immediately preceding stimulus and the idea in mind 
can be pictured as due to the effect of a previous stimula- 
tion of the same tracts, which in consequence are still par- 
tially active at the moment the new excitation is received. 
This corresponds to the fact noted in the preceding chapter 
that the nervous response continues for several seconds in 
relatively high degree and probably for a considerably longer 
time in some degree. The entering stimulus, finding these 
tracts already active, produces a greater excitation than it 
otherwise would or, if several stimuli of approximately 
equal intensity are presenting themselves, that one produces 
its effect for which the way has been prepared by this 
partial excitation. 

Attention as Facilitation and Inhibition. — The influence 
of attitude or purpose is the result of the spreading to a 
large number of associated paths of the impulse developed 
by the stimulus which arouses the attitude. One may 
think of the interaction of different parts of the cortex 
during attention as the effect of a widened associa- 
tion. As was said in the fifth chapter the excitation of a 
neurone not merely arouses those neurones which specifi- 
cally excite movements or are accompanied by overt con- 
sciousness, but it also exerts a tendency to arouse certain 
neurones and to suppress the activity of others. When one 
is asked a question, the question, by association, tends to 
arouse the possible answers. This means that the impulse 



292 FUNDAMENTALS OF PSYCHOLOGY 

spreads from the auditory neurones that receive the ques- 
tion to the others associated with it in previous experience. 
In addition, it would increase the tendency to activity in 
a number of other neurones related to the first, and would 
probably check the activity of others which were not con- 
nected with the first. This would make it very likely that 
any stimulus that affects any of the prepared neurones 
would be appreciated, while all other stimuli would be 
less likely to be noticed than they would be if there had 
been no preliminary preparation. An attitude has a similar 
effect. When in a biological laboratory, the parts of the 
cortex that have received stimulation in connection with 
the observation of animals are partially active or are at 
least prepared for activity, while other neurones are ren- 
dered less likely to respond. 

The effect of education is to prepare these systems of 
paths so that they may be excited by the particular stimuli 
or the particular occasions. It is essentially a process of 
organizing cerebral cells into groups so that one entire group, 
as well as some particular associate, may be aroused or 
partially aroused by a suitable stimulus. Each of these 
processes may be regarded as an explanation of the selec- 
tion, either from among the stimuli which seek to enter 
consciousness, or between ideas that are associated with 
the particular idea that serves as excitant. Thus on the 
nervous side, the course of impulses is determined by the 
action of very large numbers of neurones, many of them 
very remote from the neurones which are actually the seat 
of the processes attended to. The cortex acts as a unit 
rather than in parts, just as, on the side of consciousness, 
practically all experience unites in determining the course 
of any single element of consciousness. 



PHYSIOLOGICAL THEORIES OF ATTENTION 293 

REFERENCES 

Pillsbury: Attention. 

Titchener: Lectures on the Psychology of Feeling and 

Attention. 
Morgan: On Overcoming Distraction. Archives of Psychology, 

No. 35. 



CHAPTER X 
PERCEPTION 

General Remarks 

Perception may be defined as the process of becoming 
aware of an object. A perception is different from sensa- 
tion in that it is the appreciation of an object as an object, 
while a sensation is not known for itself or at least by itself, 
but is always a part of something else from which it is 
abstracted. The perception always is initiated by some 
sensation. It begins with the stimulation of some one of the 
senses. But as a result of that stimulation we add to the 
sensation a mental construction or series of mental processes 
which result in giving us the impression of a whole object. 

Perception a Process of Association. — The additions are 
of at least three kinds. In the first place, one sensation 
may fuse with others from the same or different senses. 
This is our experience when we see an object and touch it 
at the same time. The two impressions combine to form a 
single or common process. 

More frequent and more important is the second instance 
— the addition of memory images. When an object has 
been seen and touched at the same time on various occa- 
sions, we have the formation of association processes which 
makes us recall the image of the object when it is touched 
and also recall the sensations of touch, that we had received 
earlier, when the object is seen. Supplementing by memories 
or centrally aroused impressions is most frequent and most 

prominent among the elements in perceptions. We are 

294 



PERCEPTION 295 

constantly being led on from the sense impressions them- 
selves to recalled or added memories. Our perceptions are 
mosaics of sensations and memories in which we do not 
distinguish one from the other. In filling the blind spot, 
for example, we add, to the sensations received from the 
retina surrounding the blind spot, imagined processes sug- 
gested by them, and do not notice where the actual sensa- 
tions cease and remembered impressions begin. In all 
other senses we make similar additions which fuse with the 
sensations into a uniform whole which cannot be analyzed 
into parts. A perception is a fusion of sensation and memo- 
ries in which sensation and memory are indistinguishable. 
Perception Involves Wide Correction of Experiences. — - 
In the third place we find that the object recalled is usually 
corrected in ways that go beyond the mere addition of mem- 
ories. The object which we perceive is always regarded as 
existing in the outside world, and that object is seen as 
we beHeve it must exist in the outside world. In many 
cases the object, as we think it. is not as we could have seen 
it at any time in the past. The corrections could not be 
made by referring from the present group of sensations 
to a group that might have been received at any single 
earlier time. In addition we change the interpretation in 
an indefinite way to correspond to a number of different 
experiences of the object. We tend to see an object as we 
know it must be on the basis of all the experiences that we 
have had of it, rather than by correcting a single impression 
of the present in terms of a single experience of the past. 
In the interpretation we replace the group of experiences 
actually presented by another group that seems to us to be 
more in harmony with everything that we know. The 
simplest illustration that can be given is the way in which 
we see the top of a table or other rectangular surface. It 



2 96 FUNDAMENTALS OF PSYCHOLOGY 

is on the retina a figure with the front and back sides 
approximately parallel but with the other two sides slanting 
towards each other and. usually making obtuse and acute 
angles with the front. This figure is almost always finally 
interpreted as a rectangle. We could never see the figure 
in such a way as to give this impression. The nearest 
approach to it is if we should have one eye directly over it. 
Even then the sides would not be straight lines but would 
be bent because they are received upon the curved surface 
of the retina. This figure with which we replace the rec- 
tangle is something that we know from all of our experience 
must be the object as it exists in the outside world, but it is 
not known to exist in that form because it has never been 
seen in just that shape; however, when we test it by building 
it or by fitting it into corners that we know are square, it 
proves to be rectangular. In other words we accept as 
real the construction that has proved on earlier test to 
harmonize with all of our experiences of that object. We 
see and hear by replacing or correcting our sensations as 
our experience proves that we must correct them if they 
are to explain the world as we have known it. It is little 
more than fair to say that we see these corrected concepts 
rather than actual sensations, or than mere combinations 
of sensations and memories, although both sensations and 
memories are the all important components of the per- 
ceptions. Instances in which we see these corrected and 
harmonized results of past experiences will be found to be 
numerous in our discussion of perception. 

Perception Implies Movement. — These corrections in 
the light of wider experiences always involve a considerable 
amount of reference to action. The tests that we apply 
to the objects are frequently of a type to involve action. 
We know what objects are like because we try to manipu- 



PERCEPTION 297 

late them in various ways. One may go farther and argue 
that, since to every sensation there is some form of motor 
response, perception, too, must involve some motor activi- 
ties, and that these motor responses are an essential 
part of our interpretation of the object. The behaviorists 
would go so far as to add that all that there is of impor- 
tance in the percept is this reaction or group of reactions. 
Since their theory leaves Httle room for knowledge, it 
makes relatively shght difference to them whether we per- 
ceive through our movements or not. One must insist that 
response to movements modifies our knowledge and that 
the nature of the responses is an element that cannot be 
neglected in a discussion of perception, although it is not 
always possible, in fact has seldom been possible, to detect 
the elements that movement adds to the perception in 
individual cases. 

Percepts are always Things. — A fourth fact that must 
be kept in mind is that we always think of the product of 
the process that gives rise to perception as something in 
the outside world rather than as a mere combination of 
mental processes. This hardly needs to be added from the 
standpoint of common sense because everything that is 
thought of at all is thought of as having real existence, as 
being part of the real external world. Still it is an important 
fact that as we receive a sensation from the retina we never 
think of referring it to the retina alone, but always regard 
it as an object. So direct and complete is this reference 
that we do not first receive the impression with the notion 
that it might be a mere image on the retina and then decide 
to refer it to a certain distance in the outside space. The 
reference is immediate. The correct construction is seen 
at once as an object at a certain distance, without any inter- 
vening activity of thought. The mental process is made to 



298 FUNDAMENTALS OF PSYCHOLOGY 

mean an object in the outside world, and we are aware of 
the meaning alone. We know nothing of the group of sen- 
sations and images which must be the mental occasion for 
the development of the meaning. The matter might be 
put more definitely by saying that certain sensations have 
come to stand for an object in the outside world; and 
that we now accept the sensations that come in, as a sign 
that the object is present in the world without. But in all 
this, it should be emphasized that what we are immediately 
aware of is always the object that is meant and for which 
we have the sign, rather than the sensations or the signs 
themselves. These various steps and aspects of the develop- 
ment of perceptions we shall have occasion to indicate at 
each step in the examination of the concrete perception 
process. 

In discussing perception we find it convenient to consider 
certain of the general aspects of objects first and then pro- 
ceed to the more concrete phases later. All experiences 
have duration, and we in practice abstract these temporal 
phases from the particular happenings, and consider them 
apart from the events. We may conveniently discuss the 
perception of time with no reference to the filUng of time. 
Space also is involved in the perception of all objects and 
can be discussed without reference to the particular objects 
in space. Other general aspects of experience are motion 
and rhythm. Each of these can be treated apart from its 
particular content and this simplifies the treatment of the 
perception of particular objects. We may begin with the 
discussion of space. 

Perception of Space 

Problems Concerning Space. — Space is appreciated by 
means of at least four senses, — touch, vision, audition, 



PERCEPTION 299 

and the kin aesthetic sense. Of these, vision gives the most 
accurate and complete appreciation, touch combined with 
the kinassthetic impressions stands next in definiteness, 
and the auditory space comes last. In actual practice all 
objects that are recognized as objects are thought of as ex- 
isting in space, whether they are actually sensed or merely 
recalled. In the senses not mentioned, the spatial aspects 
are ascribed to one of the more definitely spatial senses; 
thus tastes are referred to the tactual impressions also re- 
ceived from the tongue, — or are somewha t indefinitely 
referred to space in general. Odors are usually ascribed to 
objects, but the localization is always uncertain and the 
quality may be thought of as independent of the organ, as 
general or all pervasive. Not only are the subordinate 
sensations referred to sight, but there is much cross refer- 
ence between the higher senses. Different senses predomi- 
nate in different individuals, but in all space interpreta- 
tions several senses are involved. 

Three different complexities of the space problem pre- 
sent themselves, although for sight and kin aesthetic impres- 
sions alone are all these problems to be considered. These 
three are the appreciation of position, of extent in two dimen- 
sions, and of distance or depth, the third dimension. The 
skin appreciates position and extent alone; the ear, dis- 
tance and direction alone. We can start with the simplest 
problem in each sense and transfer what may be gained 
from that to the more complicated constructions. 

Perception of Tactual Space. — Theoretically simplest of 
the space problems is the appreciation of the position of a 
point upon the skin. Experiments have frequently been 
made to determine how accurately a spot upon the skin 
may be localized. If one attempt to touch a spot on the 
skin, one will make an error that averages a centimetre or 



300 FUNDAMENTALS OF PSYCHOLOGY 

so on the wrist or on the back of the hand, is smaller on 
the fingers, and considerably larger on the portions of the 
body ordinarily covered. This simple experiment indicates 
two facts: first, that there must be some way of knowing 
where the point touched is and that this guides the move- 
ment; and secondly, that this localization is not absolute, 
that it is subject to error, and more or less variable. One 
of the first theoretical attempts to determine what it is 
that gives a knowledge of position was made by Lotze. 
Lotze pictured the self as somewhere in the brain and as 
receiving impressions over the nerves from the surface of 
the body. Such a self might be thought of as constantly 
questioning what part of the skin gives rise to the sensa- 
tions it received and seeking for signs that indicate their 
origin. Lotze asserted that the sensations received from 
different parts of the skin had different qualities. These 
different qualities were not described very definitely, but 
apparently were due in part to the character of the skin 
and the amount of tissue that lay between it and the bone. 
The quality of any spot on the skin he called its 'local 
sign.' If you will try to discover this local sign in the sen- 
sations from your own skin, you will find it very difficult. 
Careful examination of the sensations fails to disclose any 
such quality in addition to the ordinary skin sensations, — 
one knows immediately where the touch is but does not 
know how he knows. 

Indirect methods of analyzing the local signs or means of 
localization indicate that it is dependent in part upon the 
nerve stimulated. When a member has been amputated, 
the sensations from the stump are still referred to the miss- 
ing part, and when a portion of the skin has been displaced 
by a surgical operation without severing the nerves that 
supply it, sensations from the skin will for a time be given 



PERCEPTION OF POSITION 301 

the old position. It is true, too, that the accuracy of lo- 
calization is greatest where the nerve endings are most 
numerous. These factors might be explained on Lotze's 
assumption that each nerve had a 'local sign.' They also 
have been interpreted to mean that localization is due to 
the movements called out refiexly. If each point on the 
skin were connected with a set of motor neurones that 
would cause the hand to move to the point touched or that 
would call out a slight movement toward the point, the 
movement might be used as a sign of the position. This 
motor theory receives some support from the fact that 
animals whose brains have been removed, and men in 
their sleep, will touch the point stimulated with a fair de- 
gree of accuracy. That it alone is not sufficient is prob- 
able from the fact that the normal animal makes the move- 
ment with greater accuracy. Still a third theory would 
make the localization due to the association of other sen- 
sations with cutaneous excitation. Often a picture of the 
point touched comes immediately upon contact. However, 
no one of these theories may be regarded as sufficient in 
itself. Rather must we assume that all have acted to- 
gether to give a notion of each different position on the 
skin. As different points have been touched, the kiuces- 
thetic have been associated with the visual sensations, and 
these with the sensations of contact and with any other im- 
pressions that may be concerned. After the notion has 
been developed it is called up by any contact. 

The *Limen of Two-ness.' — Much the same problem 
meets us in connection with the appreciation of a minimal 
extent. This has been studied by determining the least 
distance at which two points might be appreciated as two. 
Weber, who made the first experiments, found that this 
distance varied from approximately i mm. on the finger 



302 FUNDAMENTALS OF PSYCHOLOGY 

tips and tip of the tongue to 40-60 mm. on the middle of 
the back. In general it was larger on the portions of the 
body ordinarily covered and, on the limbs, decreased regu- 
larly from the centre of rotation downward. Volkmann 
noted that it varies approximately with the amount of 
motion of the member and of the parts of the member in 
question. Goldscheider repeated the experiments by put- 
ting the points of a compass upon pressure spots, and 
found that two points might be distinguished when the 
points were on contiguous spots. His values varied from 
0.3-0.6 mm. on tongue and finger tip to 4-6 mm. on the 
back. Later experiments by von Frey indicated that these 
values were too small unless the stimuli were applied suc- 
cessively. In these experiments, as in comparisons in gen- 
eral, successive stimuH are judged more accurately than 
simultaneous stimuli. It is also to be noted that practice 
and suggestion have marked effects. Values may be re- 
duced one-half or more in a few weeks' practice. It is 
seen, too, that practice on one part of the body will have 
an effect upon the symmetrical areas that have not them- 
selves been exercised. 

The explanation of these values may be reduced in part 
to a matter of comparing 'local signs.' When two signs of 
position are much alike, they are confused and made to 
constitute one point. By sign of position may be meant, 
either the actual sensory qualities received from the points, 
if they exist, or the movements that must be made to 
touch each, or the suggested motion from one to the other, 
or reference to visual distances. Improvement with prac- 
tice is suggestive of this process of analysis, as is also the 
greater acuity on the more mobile and in consequence more 
frequently used members. Larger extents probably de- 
pend more upon movement from one point to the other, 



PERCEPTION OF VISUAL SPACE 303 

either of the member itself or of another exploring organ. 
A curious illusion that arises in the comparison of filled 
with empty space would indicate that the nature of the 
stimulation plays a part. If one is asked to compare a sin- 
gle empty space with a space containing other stimulated 
points, the empty space seems greater than the interrupted 
space. The explanation is difhcult in terms either of 
movement or analysis. The importance of reference to 
vision should also be emphasized. Many individuals trans- 
late cutaneous sensations into vision, and do not appre- 
ciate the distance until this translation is complete. This 
statement may be verified if one will have another trace 
outlines on the skin, or press objects of different shapes 
against it. The bhnd must of course have an immediate 
appreciation in terms of pure cutaneous impressions or of 
movements. How these different factors cooperate is not 
as yet known, but it is undoubtedly a process that is much 
more compHcated than the simple theories we have indi- 
cated would seem to imply. 

Retinal Local Sign. — If one is to explain something of 
the spatial perception on the skin by reference to the in- 
fluence of vision, it is also necessary to understand how po- 
sition and extent may be perceived on the retina. The 
same problems meet us here and many of the same facts 
are present to provide the data for discussion. There is a 
lower limit of distance that must separate two points if 
they are to be perceived as two. On the fovea if two dots 
or Hnes are nearer together than .004-.006 mm., or an an- 
gular distance of 6o"-9o", they fuse into a single line or 
dot. This may be regarded as the 'limen of two-ness' for 
sight. The effects of the inability to distinguish lines and 
points closer together than this minimum can be seen in 
the abihty to distinguish letters in reading. The normal 



304 FUNDAMENTALS OF PSYCHOLOGY 

eye can read letters when the width of the separate lines 
and the distances that separate them are each i'. The 
Snellen types in the adjoining figure can be read at a dis- 
tance such that the Hnes are separated by this amount or 
by .004 mm. on the retina. Stratton found that if two 
vertical lines placed one above the other were brought to- 
gether at their extremities, a break in the Hne could be 
noted when they were displaced 7" only. In this case, 
however, the difference in direction of the Hnes probably 

also gives a cue; it is not 
merely appreciation of the dis- 
tance between points. As the 

Fig. 71. — Snellen types. j* ^ j.\. j. j. J.^ 

distance that separates the 
centres of cones in the fovea is only about 4o"-6o", it 
would seem that stimuli no farther apart than the centres 
of neighboring cones can be discriminated. As one pro- 
ceeds outward from the fovea, the acuity diminishes very 
rapidly. Five degrees from the centre it has been reduced 
to one-fourth and at forty degrees to one two-hundredth of 
the maximum value. In twilight vision, where the cones 
are not involved, acuity is approximately the same in all 
portions of the field beyond ten degrees from the centre. 
It is zero in the fovea itself, and rises very rapidly to at- 
tain a constant value five to ten degrees distant. 

The theories of the appreciation of position and extent 
upon the retina involve the same principles as those ad- 
vanced for the skin. The awareness of position seems to 
depend in some way upon the nerve element stimulated, 
as is evidenced by the fact that when a retinal element is 
displaced it still gives the old sign of position. Thus Wundt 
at one time suffered from choroiditis under one small portion 
of the retina. This caused a swelling of the retina and finally 
resulted in a small scotoma or blind spot. While the elements 



PERCEPTION OF VISUAL SPACE 305 

of the retina were displaced in this region, the straight lines 
seen on it were distorted, and it was only after the rods and 
cones had been used in their new positions for a consider- 
able time that the spatial relations became normal again. 

Theories of Localization — This sign of position that at- 
taches to the retinal element has been ascribed to the con- 
jectural 'local sign' and to movement. Differences in the 
qualities of sensations received on different areas of the 
retina have been suggested as furnishing the means of dis- 
tinguishing position. Even the difference in the quality of 
a color has been suggested as a sign. In the movement 
theory it is assumed that the tendency of the eye to turn 
in such a way that the point attended to shall fall upon the 
fovea constitutes the mark of position. The more general 
and inclusive the final explanation, the greater the hkeli- 
hood that it will be correct. It is probable that the idea 
of position here, too, is a notion that has been gradually 
developed through experience of all possible sorts, that it 
includes reference to motion, to areas as known on the 
skin, and particularly to the movement of the fingers over 
surfaces as eye and finger explore them together, and a 
large number of more general practical tests. After the 
complex idea has developed, some peculiarity in the retinal 
element stimulated or the activities aroused by the stimu- 
lation suggest this idea or concept. Either such a highly 
complex concept of position whose origin has been lost in 
the course of its development, and which is now appre- 
ciated only for its meaning, must be assumed to constitute 
our idea of position, or we must leave the problem unsolved. 

The perception of greater visual extents depends very 
largely upon the eye movements. This phase of perception 
has been investigated with more care for the eye than for 
the skin. Studies in the comparison of two Hnes show that 



3o6 FUNDAMENTALS OF PSYCHOLOGY 

the appreciation of distance follows Weber's law, — one 
can appreciate an addition in length of from iV to iV to a 
horizontal line, an average of about sV- Appreciation of 
difference in the length of vertical lines is slightly less ac- 
curate, an average of about -^o- This shghter degree of 
accuracy in perception of vertical movements has been 
connected with the fact that the vertical movements re- 
quire two pairs of muscles and so a greater amount of ef- 
fort than horizontal movements. They are thus less accu- 




FiG. 72. — Muscles of the eye. rs, superior rectus; rif, rectus inferior; re, ex- 
ternal rectus; rit, rectus internus; os, superior oblique; oi, inferior oblique; t, ten- 
don of superior oblique which runs through the membranous pulley, u, on nasal 
wall of the socket. 

rate and more difhcult to compare. As one estimates the 
length of a Hne, the eyes move from one end to the other 
and the comparison is probably very largely through these 
movements. The quahtative characteristics or group of 
'local signs' may also be involved; but here, as in the Hmi- 
nal values, they have not been clearly discriminated. 

The Eye Muscles. — The importance of eye movement 
in the perception of space makes it desirable to give a brief 
statement of the muscular mechanism. The eye is moved 
by six muscles arranged in pairs, and named, from func- 



PERCEPTION OF VISUAL SPACE 307 

tions and attachments, the internal and external recti, the 
inferior and superior recti, and the inferior and superior 
oblique. The recti muscles all spring from near the apex 
of the eye socket and pass directly forward to their point 
of attachment on the surface of the eyeball. The superior 
oblique also originates at the apex but runs forward to a 
ring of cartilage on the upper nasal rim of the socket and 
then turns backward to be attached behind the centre of 
the upper surface of the eyeball. The inferior obhque 
springs from the lower nasal rim of the socket and passes 
back to a point behind the middle of the lower surface. 
From the fact that the obhque muscles exert their pull to- 
ward the front, they turn the eyes in the direction opposed 
to their names. The direction in which the muscles turn 
the eyeball may be best indicated by the diagram taken 
from Hering. It will be seen that the internal and exter- 
nal recti muscles turn the eye in an approximately straight 
line; all the others turn it along a curve and if the eye is 
to be moved directly up or directly down, two muscles 
must cooperate (Fig. 73). 

Eye-movements. — The eyeball turns about a point 
about 1.3 mm. behind the centre of the eye. The centre of 
rotation is 13.5 mm. back of the cornea. It should not be 
assumed that this point is absolutely fixed, — owing to the 
loose way in which the eyeball is held in its socket, it is 
slightly displaced as it turns, and the centre of rotation 
moves with it. Also as the eyeball turns, it is rotated 
more or less about its optic axis. This is called torsion. 
The amount of torsion increases with the amount of the 
movement, but is always present even for shght move- 
ments. Both eyes always move together. A single im- 
pulse is sent simultaneously to the same muscles of both 
eyes. It is as if they were a team of horses turned by a 



3o8 FUNDAMENTALS OF PSYCHOLOGY 

single pull on a pair of reins. These movements follow the 
direction of attention, as was said in an earlier chapter. 
The only conscious antecedent is that some object in the 
field of vision shall catch the attention, then the eye mus- 
cles immediately contract in a way to bring both eyes to 
fixate the object. As points of reference for eye move- 



r.ext. 



ao so 10 




10 20 00 



Fig. 73-- 



-Hering's diagram of eye-movements, showing course the eye would fol- 
low if pulled by each muscle singly. 



ments, one may distinguish certain positions. What is 
known as the primary position is that which the eyes have 
when fixed on a distant object in the median plane and a 
little (15°) below the horizontal. From this, movements 
may be made in any direction with the optic axes parallel, 
or the eyes may be converged upon points in the median 
plane or to one side of it. These positions have been called 




PERCEPTION OF VISUAL SPACE 309 

secondary and tertiary, but no agreement as to which are 
to be called secondary and which tertiary has been attained. 
The Two Eyes are One for Vision. — The fact that we 
always use two eyes instead of one offers interesting prob- 
lems as to how two impressions can combine in one, what 
part each contributes, and the advantages of binocular as 
compared with monocular vision. In general, it may be 
said that for most purposes the two eyes act almost as one 
organ. If a plane surface be presented to both eyes, we 
see it single and not appreciably different from the same 
surface as seen by a single retina. 
When different objects are presented 
to the surfaces of the two retinas, 
the result may be that (i) the two 
may fuse to produce a new quality. 

Fig. 74. — Stereoscope slide 

(2) one may suppress the other en- that shows the effect of con- 
tirely, or (3) first one may be seen, Ceri J„u°Ps,Slt°") 
then the other. Colors which fuse 

when they fall upon the same surface in a single eye are Ukely 
to fuse when one stimulates one retina, the other the other. 
For certain individuals there may be an alternation. Thus, 
if one half of a stereoscopic slide be red and the other blue, 
when looked at in the stereoscope they will ordinarily give 
a purple, but at times and in part of the field an individual 
will see first the red and then the blue. Where a contour 
of any kind is presented to one eye and a uniform surface to 
the other, as in Figure 74, the contours will be noticed and 
the plain surface neglected. The law may be formulated 
in the statement that you see what means most to you, 
what is most interesting, while you neglect the unimpor- 
tant plain surface. Where two colors or grays, alike except 
in brightness, are combined, the result is a single color with 
a brightness intermediate between that of the components. 



3IO FUNDAMENTALS OF PSYCHOLOGY 

The brightness is usually a little greater than the average 
for the two stimuli. Thus, when the two are of the same 
brightness, the brightness of the combined image may be 
To greater than that of either alone, and when they are 
very different, the brighter may have its brightness reduced 
by the darker. This latter is known as Fechner's paradox, 
since the addition of the fainter brightness to the greater 
reduces rather than increases the brighter. A contrast color 
may also be induced in one eye by stimulation of the other. 
Corresponding Points. — Very important for the space 
problems is an understanding of the arrangement of the 
points or lines that are seen singly. If vertical lines, one 
on one half, the other on the other half of the stereoscope 
slide, be seen in the stereoscope, it will be found that the 
lines will be seen as one if they are so placed that the im- 
ages fall on identical points, i.e., on points that are the 
same distance from the fovea and in the same direction. 
If both are vertical and pass through the centre of the 
fovea, they will be seen as one; if one pass through the 
fovea, the other through a point one degree to either side 
of it, both will be seen. Identical points may be defined as 
those equidistant from the fovea and in the same direction 
from it. If the two retinas could be placed one over the 
other in such a way that the foveas and the vertical and 
horizontal axes coincided, then all points that were super- 
imposed would be identical points. Stated in terms of 
rays of light, those rays fall upon identical points which 
make the same angle with the lines of sight of each eye 
and in the same direction. The line of sight is the line 
from the fixation point to the centre of the fovea. Corre- 
sponding points are those points which in practice com- 
bine to give a single image. Identical points are defined 
geometrically. Ordinarily they agree for practical purposes. 



PERCEPTION OF VISUAL SPACE 311 

A most important problem for the perception of space is 
to determine how much two stimuH may depart from cor- 
respondence before they can be seen as two; or, in terms 
of our first problem, how far the two lines on the stereo- 
scopic slide may depart from correspondence before they 
will seem to be two. Pulfrich^ and Bourdon^ found that 
two objects need have no greater deviation from corre- 
spondence than from 5" to 12" for the deviation to be 
noticed. This is considerably less than the 'Kmen of two- 
ness' for a single eye. It should be added that the lines 
are not necessarily seen as two, but the divergence may be 
translated into depth, as will be seen in a later discussion. 
Considerably greater deviations from correspondence may 
take place without being noticed if the lines are horizontal 
than if vertical. 

Why two points should thus give rise to but a single 
image is not easy to say. The first theory, suggested by 
Johannes Miiller, was that it was due to the fact that cor- 
responding points were connected with the same half of the 
brain. It is a fact that the right half of each retina is con- 
nected with the right hemisphere, and each left half with 
the left hemisphere. There is, as the diagram (p. 54) 
shows, only a partial crossing at the chiasma, — half of 
the fibres cross and half go uncrossed to the same side of 
the brain. Miiller assumed that these fibres in some way 
combine in the cortex, perhaps connect with the same 
cells, and so give rise to a single image. This would be 
the nativistic explanation; the combination would be due 
to the innate nervous connections. The empiricist, how- 
ever, can cite numerous cases in which this correspondence 
is changed by experience. Individuals whose eyes are 

^ Physikalische Zeitschrift, 1899, No. 9. 
^ Revue Philosophique, Vol. 25, p. 74, 



312 FUNDAMENTALS OF PSYCHOLOGY 

badly crossed, who squint, develop a new set of corre- 
sponding points; the points that have been used in seeing 
the same object come to give single images, or else the 
image from one eye is disregarded. Similarly, horizontal 
lines may be a considerably greater distance apart than 
vertical ones and still correspond. Under those circum- 
stances experience makes it more likely that there is one 
line than two. If the lines be vertical and deviate very 
slightly from correspondence, they will be seen as two. 
We shall see that this deviation from correspondence of 
vertical lines is an important factor in the appreciation of 
distance, and is therefore noticed; while the necessity for 
distinguishing horizontal lines is relatively sUght. The 
empiricist's explanation would be that we see the two im- 
ages as one, because tests by touch or other senses have 
shown that there is only one object present in spite of the 
two images; we have learned that two images mean one 
object, and the positions that are most frequently stimulated 
together by a single object become corresponding points. 

The Horopter. — The problems of binocular vision and 
corresponding points are of interest because of the light 
that they throw upon the positions that objects in space 
must occupy if they are to be seen singly. When the eyes 
are converged in a given position, there is only one dis- 
tance from which rays of light can fall upon corresponding 
points. The distance varies as convergence varies, but the 
locus of points in space which will send rays to correspond- 
ing points is strictly Hmited. Points nearer or more re- 
mote will fall upon non-corresponding points and so give 
double images. The locus of all points that fall upon 
corresponding points is called the horopter. The form 
of the horopter has been developed mathematically in 
great detail. Since the assumptions upon which the com- 



PERCEPTION OF VISUAL SPACE 



313 



putations are based do not correspond accurately to the 
actual facts of vision, we need pay little attention to the 
intricacies of the calculations. Two forms of the horopter 




Fig. 75. — Miiller's Horopter Circle, a and a', b and b' are corresponding points. 
Lines drawn from these points through the nodal point will meet in a circle that 
passes through the fixation point F and through the two nodal points, n and n'. 



may be mentioned. When the eyes are converged upon 
a point in the plane halfway between them, the horopter 
is a circle passing through the fixation point and the nodal 
points of both eyes. To this is added a vertical hne 



314 FUNDAMENTALS OF PSYCHOLOGY 

through the fixation point. When the eyes are parallel, all 
points at an infinite distance, the distance at which paral- 
lel lines meet, would fall in the horopter, theoretically. In 
practice, the horopter is composed of all space beyond the 
point where the departure from the parallel is less than 5", 
the least disparateness that can be appreciated, or beyond 
a distance of some 2500 metres. 

The Perception of Distance. — We have now to consider 
the application of the different facts of vision so far col 
lected to the perception of the distance of objects from us 
— which may be called depth or the third dimension. We 
may speak first of the elements which are derived from the 
structure of the eyes and which in consequence are usually 
termed the primary or physiological factors. With the 
single eye the most important is the accommodation of the 
lens for different distances. As was said in Chapter IV, 
when a near object is attended to, the ciliary muscle is con- 
tracted and this permits the lens to thicken and give a clear 
image of the object. On the other hand, when a more dis- 
tant object is attended to, the ciliary muscle is relaxed and 
the lens is flattened by the tension on the suspensory liga- 
ment and so adapted to receive a clear image from distant 
objects. The degree of strain varies inversely as the dis- 
tance, and is immediately interpreted to mean the distance 
of the object. One thinks of objects that are seen with 
much strain, as near; those that are seen without strain, as 
remote. (No strain is required for objects more than about 
50 feet away.) As is usual in all perception, these factors 
are not observed in themselves; the distance alone ordi- 
narily comes to consciousness. 

Convergence as a Factor in Distance Perception. — When 
two eyes are used for the appreciation of distance, estimates 
are much more accurate than when one eye is used. If a 



PERCEPTION OF DEPTH 



315 



man looks with one eye at a landscape, he notices that it 
appears much flatter than usual. Or if one attempts to 
put a finger through a ring held sidewise by another, it will 
be found very difficult when one eye is closed, although 
perfectly easy when both eyes are open. New factors 
obviously must be added when both eyes are used. Two 
of these are important. One is muscular, the movements 
required to converge the eyes upon a single object. Distant 
objects are viewed with the eyes nearly parallel and with 
the muscles fairly completely relaxed. As an object comes 

TABLE II 




nearer, it is necessary to contract the internal recti muscles 
that the eyes may be converged to see it with the foveas. 
This gives rise to another strain that also decreases with 
the distance. This strain is a more accurate index of dis- 
tance and can furthermore be used to detect distance over 
a longer range than the strain of accommodation. If one 
compare the distance of a thread seen at different distances 
first with one eye then with both, under conditions that re- 
strict the means of determining distance to the muscular 
adjustment, it is found that the distances that can be 
distinguished are much less in the latter case than in the 



3i6 FUNDAMENTALS OF PSYCHOLOGY 

former. This is shown in the table on page 315 taken 
from Wundt. 

The distance is the absolute distance from the eye; the 
limen, the difference in distance that can be just noticed; 
while the relative Hmen is the limen for binocular vision 
divided by the absolute distance. This, it will be noticed, 
is approximately the same as the difference limen for the 
comparison of horizontal lines on a flat surface, in which 
movements have also been regarded as an important factor. 

Double Images in the Perception of Distance. — Still 
another indication of the distance of objects is given by 
the differences in the images of the objects on the two 
retinas. One may be said to get a different image of a dis- 
tance with each eye. If one hold a ruler end on in front 
of the eyes and close first one eye and then the other, it 
will be noted that the image shifts as the eyes are changed. 
If one converges upon the far end, with both eyes open, the 
near end will be seen double, while if one looks at the nearer 
end, the farther will be double. In either case the image of 
the ruler will slant from the double to the single end. These 
double images will not be noticed at first but will be used 
as immediate signs of the distance of one end from the other. 
Similarly, if two threads are present simultaneously in 
the field of vision at different distances, the one fixated will 
be seen single, the other double, and will be separated by a 
space that increases with the distance between the threads. 
This doubleness is of value only in determining the distance 
between two objects or points, not for the determination 
of the absolute distance of a single object. The degree of 
doubleness changes with each position of the eyes as well 
as with the distance of the object. Given the absolute 
distance of any point of reference, the distance of any other 
point from that in the field of vision may be determined. 



PERCEPTION OF DEPTH 



317 



Not only may the distance between two points be estimated 
in this way but also which is nearer the observer. If one 




Fig. 76. — To illustrate crossed and uncrossed Images. F is the fixation point 
and is seen singly. An image of a more distant point A falls upon points a and a' 
on the retinas, which are non-corresponding. As excitations of the retina are pro- 
jected to the plane of the fixation point, they are seen at A ' and A " and are there- 
fore uncrossed, the image seen with the right eye is seen to the right of the fixation 
point and to the right of the image seen with the left eye. Objects nearer than the 
fixation point, as B, will also be projected to the fixation plane at B' and B " and so 
are crossed, the image on the right retina is seen as if it were to the left of the fixa- 
tion point and vice versa. 

fixate the more remote, the double images are crossed; that 
is, the one on the right is seen with the left eye, and vice 
versa. If one fixate the nearer, the more remote gives un- 



3i8 FUNDAMENTALS OF PSYCHOLOGY 

crossed double images. This can be tested by closing one 
eye. It will be noticed that when the farther object is 
looked at and one eye is closed, the image on the opposite 




Fig. 77. — Diagram of prism stereoscope. (From Titchener, " ExperimentaL Psy- 
chology.") 

side disappears; when the nearer object is fixated, the 
image on the same side disappears. This occurs because 
the double images are always referred to the plane of the 
fixation point in considering their relative position as on 
the right or on the left. This can be seen by study of the 
diagram (Fig. 76). 



PERCEPTION OF DEPTH 



319 



These double images constitute one of the important 
features in estimating depth in our ordinary perceptions. 
As one looks at any landscape with the eyes converged upon 
some object in the middle 
distance, all nearer objects 
are seen double in crossed 
images; all more remote 
objects are seen double in 
uncrossed images, and the 
degree of doubleness in- 
creases with the distance 
from the object fixated. 
These double images are 
not ordinarily seen for them- 
selves, but are at once trans- 
lated into distance, just as 
are the strains of accom- 
modation and convergence. 
However, they can be 
noticed with a little prac- 
tice. So close has become 
the association between 
double images and the per- 
ception of distance that 
when letters are printed to appear double, they seem 
nearer or farther even when viewed with a single eye. 
The importance of the double images may be shown 
by the use of the ordinary stereoscope which depends for 
its effect upon the fact that the two pictures represent 
the image that would be seen, one by the left, the other by 
the right eye, were one standing at the point occupied by 
the double camera when the picture was taken. The 
prisms in the stereoscope turn the rays of light sufficiently 




Fig. 78. — Diagram of prism pseudo- 
scope. (From Titchener, op. cit.) 



320 FUNDAMENTALS OF PSYCHOLOGY 

to have them enter the eyes as if they came from a single 
object rather than from two. The difference in the two 
pictures gives the same degree of doubleness that would be 
given by the single object, and is interpreted as distance 
just as it is in actual space perception. Increasing the 
distance between the cameras that take the pictures, in- 
creases the apparent depth. 

Pseudoscope and Teleostereoscope. — Even more strik- 
ing is the effect of the pseudoscope. If the relations of the 
double images are reversed, as may be done in the stereo- 
scope by interchanging the picture belonging to the right 
eye and that belonging to the left, the nearer objects appear 
farther away, the more distant nearer than the point of 
fixation. The same effect may be obtained with real objects 
by using the pseudoscope devised by Wheatstone. This 
consists of two right-angle prisms mounted in tubes that 
can be brought one before each eye. The images are 
reversed in passing through the prisms, and this makes 
the images that come from the nearer object enter the eyes 
as if they came from the more remote; the character of 
the double images is reversed, those from objects more 
remote than the fixation point are crossed, those from 
objects nearer than the fixation point are uncrossed. In 
consequence, the distance interpretations are also reversed. 
The inside of a mask when viewed through the stereoscope 
will appear to be the outside, the nearer of two threads will 
seem to be more remote, etc. It is to be noted that the ef- 
fect is much easier to obtain if the inside of the mask be 
painted to correspond with the design of the outside, and 
is so lighted as to avoid strong shadows. Another indication 
of the importance of double images in the perception of 
distance is furnished by the teleostereoscope. This instru- 
ment consists in principle of two pairs of mirrors, P, P, one 



PERCEPTION OF DEPTH 321 

before each eye, and another, M, M, at a little distance to 
the outside to receive the rays of light from the object. The 
effect is to increase the degree of doubleness, and to make 
the perception of distance as accurate as it would be if the 
eyes were as far apart as the more widely separated mirrors 
that first receive the rays of light. The course of the rays 
may be made out from Fig. 79. A similar device is used 
in the better field glasses at present. Surfaces of prisms 
supply the mirrors and these are separated by a much 
smaller distance to make the instrument more portable, 









H. 



L R 

Fig. 79. — Teleostereoscope. (From Titchener, op. cit.) 

but they serve to increase markedly the accuracy of the 
estimation of distance. 

These three factors, the strain of accommodating the eye 
to different distances, the strain of converging the eyes upon 
an object, and the double images, constitute the signs of 
depth that may be said to depend upon the structure of the 
organs, and are sometimes called the primary factors. They 
vary in accuracy, — accommodation is least accurate, con- 
vergence about five times as accurate, and double images 
much more accurate than either of the others. They also 
vary in the distance at which they are effective. Accommo- 
dation is an aid only for objects nearer than fifty feet; con- 
vergence is effective up to about 300 feet. Under the best 




322 FUNDAMENTALS OF PSYCHOLOGY 

conditions double images give an idea of distance up to 
about 2500 yards. Beyond that, the more distant objects 
show no appreciable doubleness of images, although of 
course all nearer objects are seen as double. In each case 
the distance alone is really seen; the strains or double 
images that have been mentioned are not noticed. The 
distance directly inferred is not any single mental image or 
sensation, any more than is the local sign, but is appre- 
ciated as distance. 

The Psychological Factors. — While these primary 
factors make estimation most accurate, many other signs 
of distance are of great value. The others consist of 
changes in the character of the image as the distance 
changes. They are the secondary or psychological factors. 
Perhaps the most important of these is perspective. The 
size of an object is inversely proportional to the distance. 
If one knows the size of any object in the field of vision, 
it is altogether possible to infer its distance from its ap- 
parent size, the size of the image. The importance of 
this means of obtaining an idea of distance may be gathered 
from the use of perspective in art. The distance ascribed 
to an object in a photograph or painting depends very 
largely upon its size, relative to other objects in the photo- 
graph. Here, as in the other factors, the estimates of 
distance are not made consciously; one does not first 
notice the diminished size and then infer how far away the 
object must be to give that distance, but sees the distance 
at once, and corrects the size of the object in accordance 
with his estimate of its distance. The object seems to be 
of full size and at the correct distance. The tendency to 
overlook the difference in size is evident from the relatively 
late development of perspective in art. The early paintings 
and bas-reliefs make distant objects of the same size as the 



PERCEPTION OF DEPTH 323 

nearer ones. Obviously the early artist had not noticed 
the phenomenon of perspective but inferred distance with- 
out knowing how. Even now an artist often draws his 
distant objects larger than they should be. 

A second factor under this head is the higher position of 
more distant objects in the field of view. Objects on a flat 
ground plane appear to rise gradually as they go away from 
the eyes and, with proper allowance for the actual height 
of the object above the ground plane, the relative height 
may be used as a measure of distance. This factor was 
recognized by the early artists. Their distant figures are 
placed higher than the nearer, an arrangement that makes 
it possible to show the more remote, as well as to imitate the 
apparent effects of distance. The haziness or distinctness 
of objects is also an important factor. This can be seen 
from the tendency to mistake distant objects for near, 
where the air is particularly clear. In theatres it is cus- 
tomary to draw a net in front of the more remote parts of 
the scene. Distant objects appear blue. Both of these 
effects are due to the absorption of light waves by the air 
intervening between the object and the observer. The 
condition is sometimes called air perspective. An element 
almost too obvious to mention, but nevertheless highly 
important in practice, is superposition. The partly 
hidden object must be more remote than the one fully 
seen. 

Motion an Aid to Distance Perception. — Motion, both 
of the observer and of the object, aids in the perception of 
depth. When the head is moved to one side, all objects 
in the field of vision are displaced in different degrees. If 
one is looking at any object in the middle distance, all 
nearer objects shift in the direction opposite to the move- 
ment, all more remote ones in the same direction as the 



324 FUNDAMENTALS OF PSYCHOLOGY 

movement. The amount of the apparent displacement 
increases with the distance between the object and the 
fixation point. When one is in rapid motion as in a railway 
carriage or an automobile and is looking at a point in the 
middle distance, there is a constant procession of the near 
objects backward and the more remote objects forward, 
at a rate that depends upon their distance and the rate of 
motion. This gives a notion of distance. When objects 
are themselves in motion, the apparent rate of motion com- 
pared with the usual rate of the object at a standard 
distance serves as an indication of its distance. When seen 
from a rapidly moving vehicle objects seem smaller than 
usual because they seem to be moving much more rapidly 
than usual. This means that they are regarded as much 
nearer than they really are, and this by the habits of per- 
spective makes them seem small. 

Shadows in Space Perception. — Another factor that aids 
in determining the form of objects in the third dimension 
is the interpretation put upon shadows and high Kghts. 
The nearer surfaces are usually well illuminated while the 
more remote are more or less in the shadow. This is trans- 
lated at once into depth or distance and the shadows them- 
selves are Httle noticed. Shadows are much used by the 
artist; in fact they are quite as important as perspective 
in enabling him to represent depth in the contour of an ob- 
ject on the flat canvas. In the real object, much depends 
upon the knowledge of the direction from which the light 
comes, or from assumptions that are made concerning the 
direction. If one will look at a cameo under a microscope 
which reverses the image, it seems to become an intaglio. 
The high Hghts fall on the side that they would were the 
depth relations reversed, and the depth is also reversed. In 
depressions made in steel by a smooth ball lighted from all 



PERCEPTION OF AUDITORY SPACE 325 

sides to give numerous reflections, it is quite easy to see 
the depression as a protuberance. 

Depth for vision, then, is appreciated by virtue of a 
number of differences in the sensations that come from the 
muscles of the eye, external and internal; in the difference 
in an object as it is seen by the right eye and by the left; 
and by a number of peculiarities of the image of an object 
that change with the distance. These sensations are not 
first seen for themselves and then associated with the idea 
of distance, but as a result of their presence the object is 
at once seen at the corresponding distance. In this respect 
the third dimension is, Hke the other two dimensions and 
the idea of position, apparently received immediately, and 
can be analyzed into its elements only indirectly. 

Auditory Space 

Auditory Perception of Space. — One other sort of per- 
ception of distance needs to be mentioned, the perception 
of the position and distance of sounds. Unhke tactual and 
visual sensations, there is in sound no really two-dimen- 
sional space, no perception of objects in contact with the 
sense organ, but merely perception of the distance and direc- 
tion of objects that give rise to sounds. These localizations 
are relatively uncertain and indefinite. One is constantly 
deceived as to the distance and direction of sounds. The 
breathing of a dog on the hearth may be mistaken for dis- 
tant thunder or some other intense but distant noise. Front 
and back are often confused. Right and left much less 
often; but still under the influence of suggestion, confusions 
of this sort are far from infrequent. Experiments indicate 
that the primary factor in the perception of distance is the 
intensity of the sound as compared with the sound given 
at some known or standard distance. This impHes, first, 



326 FUNDAMENTALS OF PSYCHOLOGY 

a recognition of the source of the sound, then an association 
between the present intensity of the sound and the distance 
that would give the particular intensity. A locomotive 
whistle has been heard at a large number of distances, more 
or less accurately observed or measured. When it is recog- 
nized, its intensity at once suggests the distance. This is 
true of any familiar sound. If the sound be altogether 
unfamihar, appreciation of distance is difhcult, although 
if it be recognized as belonging to some known class, an 
estimate can usually be made. 

The Appreciation of the Direction of Sounds. — Percep- 
tion of direction depends upon three factors, — the relative 
intensity of the sound heard with each ear, the timbre of 
the sound, and its intensity. A sound on the left will 
excite the left ear more than the right. A more ac- 
curate notion of the direction of the sound may be 
gathered from the relative strength of the effects upon 
the two ears. 

Recently evidence has been accumulating in favor of 
Lord Rayleigh's suggestion that perception of direction 
depends upon the difference in phase of the tones as they 
reach the ears. As the tones from directions other than 
directly in front or directly behind must travel different 
distances to reach the two ears, they would be in different 
phases. For example, if the difference in distance were 
half a double vibration, in length, the tone on the nearer 
ear would be pulling the drum out while that on the farther 
ear were pushing the drum in. Usually the difference in 
phase would not be so great, but always appreciable. 
Stewart ^ has demonstrated that when tones fall upon the 
two ears in different phases, the apparent position changes, 
although the real position remains constant. This is prob- 

^ Stewart, Physical Review, vol. 9, 1917, pp. 502-528. 



PERCEPTION OF AUDITORY SPACE 327 

ably even more important than the relative intensity in 
determining the direction of the sounding body. 

Distinguishing between sounds which come from in front 
and behind offers greater difhculties. With pure tones it is 
almost impossible. If two tuning forks of the same pitch 
be vibrating, one directly in front, the other directly behind, 
and one be stopped, it is almost impossible to tell which is 
still sounding. The percentage of mistakes will approach 
fifty. If the sounds be complex, are noises, or from instru- 
ments rich in overtones, fewer mistakes are made. This 
suggests that the quality of the tone is in some way modi- 
fied by the direction from which the tone comes. Angell 
asserts that this may be due to the way in which the various 
overtones are modified when the tone strikes the outer ear. 
From one direction, one overtone or group of overtones will 
be reenforced, from another direction another will be 
strengthened, and the resulting complex tones enable one 
to determine the direction. Myers^ has shown experimen- 
tally that changes in the timbre of a tone will induce changes 
in locahzation. If a tone be sounded directly in front until 
the observer has acquired practice in localizing, and then 
the component parts of the tone be changed to give it a 
different quality, the sound, although still coming from in 
front, will be locaHzed in some other position. Myers 
found, too, that when he placed short rubber tubes in the 
ears, all capacity for determining the position of sounds 
disappeared. These tubes made it impossible for the 
external ear to modify the quality of the tones or their 
intensity. Changes in the intensity of the sound also induce 
similar mistakes. The importance of the changed intensities 
is to be related to the fact that sounds from in front are 
caught by the pinna, the outer ear, and focussed into the 
^C. S. Myers, Proc. Royal Society. B. vol 88, 1914; pp. 267-284. 



328 FUNDAMENTALS OF PSYCHOLOGY 

meatus, while sounds from behind are diminished in volume. 
When the absolute intensity and the distance of a sound 
are known or may be approximated, the position of the 
sound as in front of or behind the plane of the ears can be 
appreciated in terms of intensity. Direction of sounds, 
then, is appreciated by means of the relative intensities of 
the tones as heard by the two ears, and by the timbre and 
intensity of the tone. It has at times been assumed that 
direction might be known by means of the stimulation of 
the skin in the neighborhood of the ears, or on other portions 
of the face. This assumption is improbable in itself, since 
sound waves are not sufficiently intense to excite the organs 
of pressure. 

The Auditory Space of the Blind. — Auditory apprecia- 
tion of space plays a much larger part for the blind, who 
must trust to the ears for a knowledge of the position of all 
distant objects. A blind man appreciates the distance of 
objects fairly accurately through the effect they have upon 
the quality of familiar sounds, such as his footsteps or 
the tapping of his cane. Large objects reflect the sound, 
give echoes, or modify its quality. It is easy to distinguish 
the difference in the voice when speaking in a room filled 
with people and when speaking in an empty room. Even 
the presence of furniture in a room in an ordinary dwelling 
has a pronounced effect. The blind man learns to distin- 
guish all of these differences and to learn what they mean 
as to the presence and arrangement of objects. That the 
blind depend upon the reflection of sounds in avoiding 
objects was shown by Dr. Heller, ^ director of a blind asy- 
lum, who on one occasion provided his pupils with felt 
slippers in place of their heavy shoes and watched them at 
their play. He found that they no longer avoided obstacles 
- Keller, Studien zur blinden Psychologic. 



OPTICAL ILLUSIONS 



329 



and would come into conflict with many of them. The 
sound from their footsteps could no longer be heard suffi- 
ciently for the modifications by the obstacles to be noticed. 
It seems, then, that for the blind much of the perception of 
space depends upon the modification of the sounds of the 
footsteps and of other familiar sounds, by walls and objects 
in general. 

Illusions in Space Perception 

Optical Illusions. — Very interesting as illustrating the 
factors that lead to the perception of space and of perception 



A 



D 





Fig. 80. — Illusions due to overestimation of the vertical. (From Titchener, op. cit) 

in general are certain illusions of visual space perception. 
Many more forms of optical illusion are known than we can 
describe, and more explanations have been offered than we 
have room to mention, but we may select a few illusions as 
illustrations of the more important theories. One of the 
simplest types is seen in mistaken estimates of the length 
of lines, or distances between dots. Thus horizontal fines 
seem shorter than vertical fines of the same length (Fig. 80, 
A, D); interrupted spaces seem longer than uninterrupted 



330 FUNDAMENTALS OF PSYCHOLOGY 

or unfilled spaces or lines. Figure 8i, A, B, indicates that 
filled space, space filled with a number of dots, or a solid 
line seems longer than the empty space of the same length; 
Figure E, that a square with numerous vertical lines drawn 



^^^Bi^Hi^^^^^HH^^^^^Hl 



Fig. 8i. — Illusions of filled and empty space. (From Titchener, op. cit.) 

across it seems longer than it is high. Even these simple 
illusions have given rise to much difference of opinion. One 
theory would explain all in terms of eye movement. It is 
said that the fact that the up-and-down movements of the 
eyes involve a waste of effort, owing to the tendency of 
each superior and inferior rectus muscle to pull the eye in 
as well as up, a tendency which must be counteracted by 



I 



OPTICAL ILLUSIONS 331 

the oblique muscles, and so give rise to greater amounts of 
strain, leads to the overestimation. Experiments made with 
the observer lying on his side which show that the vertical 
distance is still overestimated would tend to disprove this 
theory. Helmholtz suggested that the overestimation of the 
vertical was due to a habit derived from the use of perspec- 
tive. Vertical Knes in space, as in a picture, usually or fre- 
quently represent greater horizontal distances seen in 
perspective, and so we form the habit of overestimating all 
vertical lines. 

According to one theory the interrupted spaces are made 
to seem longer by a similar exaggeration of the apparent 
movements through the numerous stops that are made at 
each of the intervening dots or Hues. That this is not the 
whole story can be seen from the fact that where the dots 
are relatively few (Fig. Si,D), one or two only in the length 
of the Hne, the distance is underestimated rather than over- 
estimated. The other explanation is that the filled spaces 
give an impression of multiplicity and this is confused with 
the length of the line. The apparent shortening of the line 
when only one or two dots are inserted is seemingly due to 
a confusion between the separate spaces and the total 
length. The full line tends to be compared with the smaller 
divisions of the divided line. This same confusion is better 
illustrated in the comparison of the vertical and the horizon- 
tal Hues in Figure 80, E. Here the vertical is compared 
with the halves of the base line. Where erected at the end 
of the line, the vertical is shghtly overestimated but rela- 
tively very sHghtly (Fig. 80, D). This effect can be elimi- 
nated by turning the book ninety degrees, while the illusion 
in E persists. 

The Miiller-Lyer Illusion. — One of the most striking and 
most discussed of all is the Miiller-Lyer illusion. It will be 



332 FUNDAMENTALS OF PSYCHOLOGY 

noted that the Hne, bounded by oblique lines that turn in, 
seems much shorter than the other hne of the same length 
bounded by obhque lines that turn out. The explanations 
offered for this illusion include practically all that may be 
offered for any. Wundt suggested that it was due to eye 
movements, that the eyes were checked too soon by the 




Fig. 82. — Various forms of the Miiller-Lyer Illusion. 

lines that turn in, and carried on by the lines that turn out. 
It is suggested that it can be explained on the basis of per- 
spective; that one represents an open book or similar figure 
with the back towards the observer, the other an open book, 
much larger, with covers opened towards the observer. In 
the first case the actual length of the book is the length of 
the line itself; in the other, the length would be from the 
end of the obhque Hnes at their greatest separation. Still 



OPTICAL ILLUSIONS . 333 

another theory is that one confuses the whole spaces 
between the obHque lines with the horizontal lines and really 
makes a judgment of the spaces, although it is assumed 
that the lines are being compared. This is one application 
of the so-called theory of confiuxion and contrast. It is 
an instance of the confiuxion phase of the theory, i.e., 



« 




6 - 


1 


1 


c 

T 


a 









Fig. 83. — Contrast illusions. (From Titchener, op. cit.) 

of the tendency to confuse something in the surroundings 
with the part of the figure that is to be judged. 

The eye-movement theory is in this case rather far- 
fetched. Dawes-Hicks found that the illusion persisted 
when the figures were exposed for too short a time to permit 
the eyes to move. And while Judd found that moving 
pictures taken of the eyes while the figures are being com- 
pared showed movements that in many instances corre- 
spond to the illusion, he concluded that the movements are 



334 FUNDAMENTALS OF PSYCHOLOGY 



due to the illusion rather than the illusion due to the move- 
ment. The perspective theory serves to correlate a number 
of different illusions, and perspective may have some influ- 
ence, but it is hardly to be regarded as the only explanation. 



o 





Fig. 84. — Contrast illusions. (From Titchener, op. cit.) 

In a wide sense, the confiuxion theory comes to mean that 
factors, other than those immediately compared, play a 
part in determining the comparison, and in this form, it 
would include the perspective element as well as any other 






Fig. 85. — Illusion due to confiuxion. (From Titchener, op. cit.) 

considerations which might aid in controlling the judgment. 
On the whole it more nearly corresponds to the facts. 

Illusions of size that illustrate the effect of contrast are 
seen in the lines of Figure 83 and the circles of Figure 84. 



OPTICAL ILLUSIONS 



335 



The distance between two short Hnes seems much longer 
than one of the same length between two long hnes. Much 
the same effect is obtained with the circles. In Figure 85, 
when the two circles are put together to form a band, the 
one seems larger, the other smaller, than when separate. 
When together, the observer confuses each with the center 
of the ring, and so tends 
to judge each as the aver- 
age between them (con- 
fluxion). When a circle 
is surrounded by a series 
of very small circles, its 
size seems to increase as 
compared with the same 
circle near a single much 
larger one (contrast). 
(Fig. 84.) 

Angle Illusions. — Illu- 
sions of direction are also 
numerous. They may be 
illustrated by the Zollner 
illusion (Fig. 86), the Hering figure, the Wundt figure (Fig. 
87, A and B), and the Poggendorf figure (Fig. 88). The 
eye-movement theory, the perspective explanation, and con- 
fluxion have all been used as explanations. The eye-move- 
ment theory holds that the eyes are distracted by the cross 
lines; but why they should be is not made particularly clear. 
The perspective theory may take two forms. Each of the 
first three figures may be seen as if drawn in perspective; and 
inasmuch as the parallel lines do not converge as they should 
to harmonize with the perspective, it is assumed that they 
must diverge. Still another apphcation is that the whole 
figures may be explained as due to the overestimation of 




Fig. 86. — Zollner 's Illusion, 
ener, op. cit.) 



(From Titch- 



336 FUNDAMENTALS OF PSYCHOLOGY 

acute angles and the underestimation of obtuse angles. It 
will be seen that this is what really happens in each case. 
But it may be said, in addition, that the estimation of the 



^^m^ 





Fig. 87. — Hering's and Wundt's figures. (From Titchencr, op. cit.) 

angles is made on the assumption that whenever two lines 
cross at right angles and are distorted by perspective, the 
figure represents two lines crossing at right angles as seen 
with the horizontal line in an oblique plane. This can be 
made out in Figures 89 and 90, where the two lines can 



THEORIES OF SPACE 



337 



easily be imagined to represent two lines crossing at right 
angles. Since all angles made by straight lines are likely to 
indicate right angles seen in perspective, we have acquired 
the habit of overestimating acute and 
underestimating obtuse angles. The 
Poggendorf illusion readily falls under 
this explanation. The lines do not 
meet, because each is turned toward the 
horizontal; and they are turned toward 
the horizontal by the overestimation of 
the small angles; or to go back to the 
explanation of that tendency, one in- 
clines to see it as if it were really more 
nearly perpendicular to the vertical line. 

These illusions, then, are all due to 
the fact that interpretation tends to 
become mixed with sensation, and that 
one cannot keep attention fixed exclu- 
sively upon the essentials of the figure, 
but is misled by its surroundings. Mixed 
with the confusion of part with the 
whole, we always find the tendency to 
see what the figure means rather than 
the figure itself, and to believe that it means something 
different from what it actually represents. The various 
special theories, perspective, confusion, or confluxion, even 
eye movements, are but special forms of this general 
tendency. 

General Theories of Space Perception. — A more ab- 
stract problem naturally arises at the end of a statement of 
the particular facts of space perception, — the question, 
what is the idea of space itself. Two schools have contended 
over this question since the beginnings of modern philoso- 




FiG. 88. — Poggen- 
dorf's Illusion. (From 
Titchener, op. cil.) 



338 FUNDAMENTALS OF PSYCHOLOGY 

phy. One, the nativistic school, insists that the capacity to 
appreciate space is born with us, and may be used without 
preliminary practice. It may be dependent upon inherited 
characteristics of our nervous system, or may be an original 
mental activity. The other school, the empirical, asserts 
that the notion of space is developed through experience, 
— must be derived in some way from the conditions of 




Fig. 89. — Bering's angle illusions. Careful observation shows that any of the 
oblique lines may be interpreted as crossing in some other than the plane of the 
page. (From Titchener, op. cit.) 

perception. For the nativist, space offers no problems; it 
is appreciated at once, as color is appreciated. For the 
empiricist, it is necessary to discover the components of the 
space idea and also to determine how a particular space idea 
is suggested. The concrete evidence for neither position is 
conclusive. The empiricists point to the numerous cases 
of error in judgment, and the cases in which appreciation of 
space may be shown to depend upon definite sensations and 
particular associations. The nativist contents himself with 
the statement that the factors which according to the em- 



THEORIES OF SPACE 



339 



piricist compose space are altogether different from space 
as we know it, and also that it is inconceivable that space 
can be derived from anything not itself spatial. 

The Space Discrimination of Those Born Blind. — The 
problem cannot ordinarily be approached directly, since 
the child has already developed his notion of space before 
he is able to tell us about it, and adults 
when questioned will have long forgot- 
ten what their first experiences were 
like and how they developed spatial 
ideas. As early as the seventeenth cen- 
tury, Locke suggested that if one could 
find a man who had been born blind 
and recovered his sight after he became 
able to describe his experiences, it would 
be possible to say how much of space 
perception was innate and, if it proved 
not to be innate, how it was acquired, 
number of cases of this sort have been observed. The 
lens of the eye is occasionally opaque from birth and may 
be removed by an operation, and the patient be made to 
see. There is no great agreement as to what the patient 
can see, but the following statements seem to be in 
harmony with most results. The shape of objects is 
not recognized at all. One patient could not tell a 
square from a circle untiil he had had a chance to touch 
each. The field of vision is described as a confused 
mass in which everything seems to be in irregular move- 
ment. Some patients are said to notice the difference be- 
tween geometrical figures when they cannot say in what 
that difference consists. One, after being told what an an- 
gle was, could count the angles on a figure and thus distin- 
guish a triangle from a square, but for some time after- 



DRIVE 

SLpWLYI 



Fig. go. — The trans- 
formation of right an- 
gles in natural objects 
seen in perspective. 

Since then a fair 



340 FUNDAMENTALS OF PSYCHOLOGY 

wards was not able to distinguish without this counting. 
The perception of distance was defective in each instance. 
Objects seemed in most cases to touch the eye, and in no 
case were they projected beyond the reach of the patient. 
There is practicaUy no appreciation of depth. When all 
the evidence has been assembled, neither school is alto- 
gether convinced of the falsity of its own position. The 
nativist argues that the patient sees so Httle, because he 
transfers the associations developed by touch to sight. The 
patient thinks objects must touch his eyes because they 
touch his skin. The empiricist, on the contrary, argues 
that the patient would see nothing were it not for this 
same earlier experience, that interpretation from tactual 
experiences and from the light that comes through the 
lenses before the operation makes possible even such im- 
perfect spatial judgments as are made. 

The attempts made by the empiricist to explain or an- 
alyze the spatial experience have for the most part con- 
sisted in reducing the various forms into some single one. 
Movements or memories of movements are most frequently 
asserted to constitute the essential idea of space. Double 
images, according to the theory, give an i'dea of depth be- 
cause they call up the memories of old movements of con- 
vergence or of the reaching movements required to obtain 
the object. That such transfers from one sense to another 
do take place is readily observed. Most persons use a 
visual space, although a motor-minded individual may 
translate visual and tactual distances into kinesthetic 
terms. But, after all, translation from one space to an- 
other does not solve the problem of space. No one sense 
gives a more direct and intuitive knowledge of space than 
any other. Vision is probably more dehcate in its appre- 
ciation, while movement demands an accuracy in space es- 



THEORIES OF SPACE 341 

timates to be adequate; but it cannot be said that the ac- 
curacy of the one or the needs of the other constitute it 
the intuitive space sense. 

We may reduce the problem of the origin of space to its 
lowest terms, if we see that there are three essential ele- 
ments in the spatial experience. These are the sensation 
or sensory cue, the idea or notion of space, and the associa- 
tion between them. Some sensory cue must always be 
present to suggest the idea. Contact on a spot calls up 
the idea of position; double images, strains of accommo- 
dation and convergence arouse the idea of distance. The 
question as to what is innate and what derived from ex- 
perience, may be considered separately for each of these 
cases. We may assert at once that the connection is de- 
rived through experience. Illusions show that the asso- 
ciates may be misplaced — the wrong idea may be called 
up by any cue — and an innate capacity to make mis- 
takes is not desired by the most ardent supporters of a 
nativist theory. 

That the exciting cause of all perception, a bare sensa- 
tion or sensory stimulus, depends upon the physical struc- 
ture of the sense organ or the nervous connections, and to 
this extent is innate, no one will deny. The case for the 
idea is not so clear. Whether this be innate or derived is 
the real crux of the problem. The argument that it is de- 
rived must give over any attempt to reduce it to a single 
element or even to a combination of different elements 
which preserve their original character. Space cannot be 
movement, it cannot be sight or touch. Judd has sug- 
gested that it is not a movement but an organized system 
of movements in which the various contradictions have 
been removed and suited to all possible occasions for ac- 
tion. 



342 FUNDAMENTALS OF PSYCHOLOGY 

Space an Integrating Concept. — If we accept this state- 
ment as far as it goes, we must add to it that space is an 
organization of experience as a whole, sensory as well as 
motor; and that there results from it not movement, but 
a concept or notion which not merely prepares for action 
but makes it possible to represent all spatial experiences 
consistently and harmoniously. We may use it for our es- 
timates of space, as well as in the control of movements, 
— for the combinations of the mathematician as well as 
for the actual structures of the engineer. What the actual 
content of this idea is cannot be asserted. Like most con- 
cepts, it is more important for the things it represents than 
for itself. It probably varies in many respects from indi- 
vidual to individual. It is certainly more highly devel- 
oped for the mathematician than for the common man, 
and more highly developed for the adult than for the child, 
for the civilized man than for the savage. The process of 
development has probably been to accept some simple idea 
or even sensation, and to use it until contradictions ap- 
pear. These contradictions are obviated by changing the 
notion until something that avoids the difficulties is hit 
upon, and this is again changed as occasion arises. The 
concept always grows out of practical needs, whether sen- 
sory or motor. Thus images on the retina are given a size 
that can be most readily fitted into our conception of the 
field of vision as a whole. Small objects are usually seen 
as if they were at about arm's length or where they can be 
easily manipulated, houses at a distance that gives us a 
good view of them; and, in thought, these various typical 
distances or sizes are used in place of the sizes of the im- 
ages on the retina. They are what are called the real sizes 
of the objects. Similar notions develop for position, for 
extent, and for depth. They are changed and adjusted 



THEORIES OF SPACE 343 

until they satisfy the conditions of movement, of sight, 
and touch, and of the practical and theoretical needs of 
every sort. In the final concept, Httle if any trace of the 
particular ideas need be left, certainly nothing that can be 
analyzed out of the concept by direct introspection. It 
represents the various experiences as corrected by different 
tests, but it is not compounded out of them. Our choice 
as to the real nature of space Hes between these alterna- 
tives: the assumption, on the one hand, that it is a con- 
cept that has developed out of experience by innumerable 
trials that finally give rise to a system of ideas which sat- 
isfactorily represents space; and on the other hand, the 
nativist position, that an appreciation of space is given 
once and for all, and that we certainly cannot explain it; 
we can at most watch its development. The former ex- 
planation seems to the writer to offer the possibility of a 
real explanation; the latter gives up the problem as in- 
soluble. 

REFERENCES 

James: Principles of Psychology, Vol. II, pp. 134-282. 
Ladd-Woodworth: Principles of Physiological Psychology, 

pp. 380-469. 
Witasek: Raumwahrnehmung. 
Bourdon: La Perception visuelle de I'espace. 
Helmholtz: Physiologische Optik., Vol. III. 



CHAPTER XI 

PERCEPTION {Continued) 

Perception or Movement 

Visual Perception of Movement. — How the eye appre- 
ciates movement is a problem closely related to the percep- 
tion of space; in many ways it is intermediate between 
the perception of space and of time. Two forms of move- 
ment must be distinguished: one in which the movement 
can be actually seen; and a second in which movements 
are so slow that one infers that the object has moved from 
the fact that its position changes between two observa- 
tions. The movement of a meteor belongs in the first 
class; that of the sun in the second. The slowest rate 
that can be really seen is one angular minute per second. 
Movements may also be too fast to be seen directly. An 
electric spark moving more than 15" in a thousandth of a 
second cannot be seen to move. Nothing more is seen 
than the path. Three different theories of how we per- 
ceive the intermediate rate may be mentioned. The first 
holds that the eye follows the moving object, and that ap- 
preciation of the movement of the eye gives also a knowl- 
edge of the movement of the object. This theory is very 
direct, but depends for its acceptance upon proof of abihty 
to appreciate the movement of the eye muscles. Recently, 
various bits of evidence indicate that movements of the 
eye muscles are much less accurately known than has been 
sometimes assumed. In the first place, there is Httle ac- 
curacy in estimating the movement of an object when il 

344 



VISUAL PERCEPTION OF MOVEMENT 345 

stands alone in the field of vision. A faint light moving in 
the dark may seem to move much more slowly than it 
really does; and, on the contrary, a stationary Kght in the 
dark may seem to be moving. If two faint lights are at- 
tached to the ends of a rod revolving about a point near its 
middle, the appreciation of the movements is uncertain. 
Either light may seem to move, while the other is station- 
ary, or the motion may be divided between them in any 
proportion. When only two Kghts are in the field, one 
sees the relative but not the absolute motion. When sta- 
tionary objects are in the field, it seems that the move- 
ment of objects is determined by their relation to the fixed 
objects in the field of view, rather than by following the 
object with the eye, and appreciating the movement 
through the contraction of the muscles. 

The After-image Theory. — Stern, among many other 
writers, has suggested a second theory, — that movements 
are appreciated through the after-images which the mov- 
ing object leaves upon the retina. Watch any object in 
fairly rapid motion and you will notice that it leaves a 
trail of after-images as it moves and that its course can be 
distinctly made out for a few moments by means of this 
trail. The motion of the moving picture is due, on this 
theory, to the fact that the separate pictures of the object 
also leave a line of after-images and that these are inter- 
preted to mean motion. The motion seems continuous if 
the separate images succeed each other with an interval of 
no more than fifteen thousandths of a second, a rate much 
higher than that ordinarily used in exhibitions, fifteen to 
twenty per second. This theory may be applied to ex- 
plain the differences between the three kinds of motion: 
movements too slow to be seen must leave no after-image 
that can be noticed; while in movements too fast to be 



346 FUNDAMENTALS OF PSYCHOLOGY 

seen, no distinction can be made between the after-image 
and the primary stimulation, the whole course is of ap- 
proximately the same intensity; only when the after-images 
actually outline the path of the moving object on the ret- 
inas, in motion of moderate rate, do we actually see move- 
ment. The trail of after-images also affords a means of 
determining the course of the motion. It is more intense 
near the stimulus and becomes gradually fainter the greater 
the distance from the stimulus. After-images, then, are 
interpreted as motion, and the direction of the motion is 
assumed to be from faint to vivid images. 

After-images of Movement. — That motion itself has an 
after-image is an important fact for the theories of move- 
ment, and its study has contributed much to the explana- 
tion of movement in general. If one look for several sec- 
onds at any moving surface, the paper on a kymograph, a 
stream, or at a revolving spiral, and then look away at a 
stationary surface, there will seem to be a movement in 
the opposite direction. Two explanations of this phe- 
nomenon have been offered; that it is due to the reversal 
of the after-image, and that it is due to an actual displace- 
ment of retinal elements by the motion, followed by their 
return to the original position when the movement ceases. 
Visual after-images change from positive to negative 
shortly after the stimulus is removed, as will be remem- 
bered from an earlier chapter. If in the original motion 
the after-images near the object are dark, and the more 
remote are brighter, in the negative after-image the dark 
portion becomes bright, and so the more remote parts will 
appear brighter. The negative after-image of brightness 
accounts for the apparent reversal of the movement. 

The Theory of Retinal Streaming. — That the percep- 
tion of movement and the reversal of direction in the 



VISUAL PERCEPTION OF MOVEMENT 347 

after-image are due to actual movement of elements in 
the retina has been asserted for some time and has been 
strongly supported recently by Ferree and Hunter. This 
is our third theory of the perception of movement. The 
evidence in its favor is the great vividness and persistence 
of the sensory processes, particularly in the after-image of 
movement. These observers assert that when the after- 
image of motion is well developed, there seems to be a 
veil of objects streaming over any surface looked at, and 
that it would be impossible for after-images or any of the 
other factors suggested to persist long enough or be suf- 
ficiently realistic to account for the effect noticed. On the 
other hand, they admit that what we know of the retinal 
structure gives no evidence in favor of an actual movement 
of its elements. Altogether the after-image theory seems 
more plausible. After-images are known to exist and 
must aid in the perception of motion. The 'only question 
is whether they account for all of the observed phenomena. 
We may at least accept the after-image theory as the most 
probable at present for the explanation of all perception 
of movement. 

Considering the problem of how we see movement at all 
to be settled, it is still necessary to consider how we distin- 
guish between possible interpretations in actual movements. 
Many of the phenomena may be the result of several dif- 
ferent conditions in the outer world. Either the eye or the 
field of vision may be in motion when many objects are 
leaving after-images. We may distinguish three conditions 
of motion, if we consider only the movements of objects 
and of the eyes. The eye may be stationary and one ob- 
ject in motion; the eye may be in motion, following one 
object, perhaps, while the rest of the field is stationary; 
or, finally, the eye may be following one object while other 



348 FUNDAMENTALS OF PSYCHOLOGY 

objects are moving in different directions or at different 
rates. 

The first case has been discussed above. In the second 
case, one would have a clear image of the object that was 
pursued by the eye, while all other objects would be seen 
in blurred images or would be leaving after-images. Here 
we must explain how we know that the eye is moving. 
This might be, either through the sensations from the eye 
muscles, or by the after-images, or other signs of move- 
ment developed on the retina by stationary objects. The 
clear image of the object in flight would show that it was 
being properly followed, while the after-images of all other 
objects serve as an indication of the movement of the eye. 

Still more complicated, but nevertheless capable of ex- 
planation along the same Unes, is the problem offered when 
the object and eye are in motion in different directions or 
at different rates. Here the total estimate is based on a 
comparison of the movement of the eye with the displace- 
ment of the image. In each of these cases much depends 
upon the estimate of the probabihty of movement. Even 
when it is a question whether the motion is of the external 
object or of the observer, interpretation is important. If 
one stands on a bridge over a rapidly running stream, it 
is quite easy to ascribe the motion to the bridge. The 
probabilities in the light of frequency of occurrence are 
that a small object like a bridge will be in motion rather 
than the larger river. Similarly, when you are on one of 
two trains standing in a station, and one starts, motion is 
ascribed to one or the other in accordance with your ex- 
pectations. Not merely the sensory elements that give 
the perception of motion must be taken into account, but 
also the estimation through early experience of the prob- 
ability that the object is or is not likely to move. 



THE NATURE OF RHYTHM 349 

REFERENCES 

Ferree: The Streaming Phenomenon, Amer. Jour. Psych., 

Vol. 19. 
Hunter: Retinal Factors in Visual After-Movement, Psychol. 

Rev., Vol. 22, p. 479. 
Wohlgemuth: On the After-Effects of Visual Motion, Brit. 

Journal of Psychology, Monograph Suppl. I. 

Rhythm 

Most series of excitations which repeat themselves at 
short intervals tend to fall into rhythm. Rhythm needs 
no description, and one could not be given if demanded. 
Two factors may be distinguished in rhythm, the grouping 
of the single elements into units, and the accenting or em- 
phasizing of one or more of the units. Auditory and kinaes- 
thetic impressions show rhythm most easily; tactual and 
visual, not so markedly. The accentuation in rhythm may 
be produced in a number of different ways all of which 
give the same effect. It can be given subjectively as well 
as objectively. If one listen to the ticking of a clock or 
the beats of a metronome, it will be noticed that they tend 
to form units, and that the character of the unit, the sound 
that is accented, will vary from time to time, and within 
limits, can be changed at will. Objectively, it is possible 
to emphasize one unit in the measure, either by increasing 
the intensity of the note to be accented, or by increasing 
the length of the note. This is evidenced by a comparison 
of ancient with modern verse. While the former produced 
its rhythmic effect by lengthening the syllable, English 
poetry obtains the same effect by increasing the intensity 
of the syllable. A similar difference in the way of produc- 
ing effects can be seen in music of the organ and of the 
piano. On the organ the intensity is constant, rhythm is 



350 FUNDAMENTALS OF PSYCHOLOGY 

obtained by increasing the duration of a tone, while on the 
piano, accent is given by increasing the intensity of the 
note. The rhythm is the same in both cases. In fact, men 
who have played the organ for years often do not notice 
either the difference in the effect or in the way in which it 
is produced. Not only may accent be given by changing 
the character of the note, but also by changing the inter- 
vals between the notes. In a measure of three notes of 
the same intensity and duration, if the first interval be in- 
creased, the first note will be accented; if the second in- 
terval be increased, the last note will be accented. 

The way in which groups are formed in regularly recurrent 
sensations may also be reduced to certain laws. The more 
rapid the rate of succession, the greater the number that 
may be brought into a single unit. In very rapid beats of 
the metronome, two hundred per minute or so, it is possible 
to combine as many as eight beats in a single unit. The 
size of the unit may be varied at will within limits. When 
they are sixty or less per minute, it is with difficulty that 
two may be grouped. In general, Woodrow found that in 
a series of tones separated by equal intervals in which every 
other note or every third was more intense, the group would 
begin with the more intense tone. When intensities were 
equal but alternate notes were longer, the longer note would 
start the measure. The grouping and the accent depend 
upon both objective and subjective factors. 

The Theories of Rhythm. — Two theories to explain these 
various facts of rhythm are at present current. One is that 
rhythm has a motor origin, that the impulse to beat time is 
universal, and that any external series that will call out this 
tendency produces the rhythm. Genetically, it is argued 
that rhythmic movements are inseparable from bodily 
activity, that the movements in physical labor came to take 



PERCEPTION OF RHYTHM 351 

on a rhythmic form, and this may have been transformed 
into the dance, which in primitive races is frequently derived 
from the daily work, and that it then was introduced into 
music and reached its present degree of complexity. 

The other theory, based on attention, develops from the 
fact that most of the factors which induce accentuation 
also give rise to attention. Both intensity and length of 
stimulus were found among the objective conditions of 
attention. More striking is the evidence from the effects 
of the preceding and succeeding interval. A period of expec- 
tation is an important factor in arousing attention. Where 
a note in the rhythmic group has been preceded by an inter- 
val, expectation increases regularly during the preliminary 
wait; and when the stimulus finally makes its appearance, 
it is more fully attended to and seems more intense than 
impressions that have been preceded by the shorter interval. 
Less obvious is the explanation of the effect when a longer 
interval succeeds the stimulus. This seems to offer oppor- 
tunity for full attention to the effect of the stimulus after 
it has stopped, and this is supposed also to increase its 
apparent intensity. It seems probable, from observation 
and particularly from the fact that an interval affects the 
accent of the note that preceded, that the appreciation of 
the rhythmic unit takes place at the end of the measure. 
The unit is heard as a whole at the moment it is completed 
rather than bit by bit as each impression comes to conscious- 
ness. The attention theory, then, would hold that rhythm 
is induced by any circumstance that makes some one or 
more elements in the series of tones occupy a more impor- 
tant place in consciousness than the others, and that the 
whole group becomes a unit for attention. 

While the attention theory has some advantages in 
explaining why the emphasis comes as it does, it seems 



352 FUNDAMENTALS OF PSYCHOLOGY 

probable that a considerable portion of the sensory content 
of the rhythm is supplied by the motor contractions which 
may come as a result of the subjective accentuation. A 
good case can be made for either theory, and they are not 
at all contradictory or out of harmony one with the other, 

REFERENCE 

WooDROw: A Quantitative Study of Rhythm: Archives of 
Psychology, No. 14. 

Perception of Time 

Problems Concerning Time. — Time offers many of the 
same problems as space. It, too, is a universal characteris- 
tic of all our experience, and there has been the same dis- 
cussion as to whether it has real existence or is merely 
subjective. As with space, we may ask how short a time 
can be noticed, and how we appreciate longer intervals. 
The traditional question, how short a time may be expe- 
rienced, receives a different answer for each of the senses 
and combinations of senses. It is much shorter for hearing 
(.002) than for sight (.044) and may rise to 0.16 second when 
one stimulus is given by sight, the other by the ear. When 
one turns to a study of the longer times, it is found that the 
estimation of time and even our awareness of the passage 
of time vary greatly with the duration of the intervals 
involved. If one is asked to hsten to times of different 
length, certain times are at once pronounced very short, 
too short to be perceived with comfort, others as too long 
to be easily appreciated. Times under 5500" (o" means 
thousandths of a second) seem too short, are hurried, and 
not adequately comprehended. On the other hand, times 
over about 18000- seem very long, and it is with difhculty 
that they can be brought within the span of comprehension. 



PERCEPTION OF TIME 353 

At about four seconds, it is no longer possible to bring the 
events within a single compass; one reaches the limit of a 
single span of time so far as it can be experienced. It 
should be noted that this is also approximately the length 
of the primary memory. Within this period events may 
be held in a single span of memory, and the memory image 
can be used with the same care and certainty as a sensation. 
It is by virtue of this fact that it is said to constitute the 
immediately experienced present. 

The Different Ways of Perceiving Time. — The point 
of division between the hurried and the comfortable time 
is of interest for another reason. It is found that if one 
attempts to compare times under 0.6-0.75 second, there 
is always a tendency to overestimate the first ; while similar 
comparisons of times, greater than this indifference time, 
lead to the underestimation of the first. This time ap- 
proximately coincides with the point of division between 
the times felt as very short and those which seem of moder- 
ate duration, and furnishes additional evidence that there 
is a real difference in the means of estimating times above 
and below. Some hght may be thrown upon the conditions 
of the perception of time by a study of the factors that 
influence the comparison of intervals. First, anything 
that influences expectation is important. Thus, if sounds 
are separated by equal intervals and every alternate note 
is more intense, the interval that precedes the more intense 
sound will seem to be lengthened. This has been explained 
as due to the surprise induced by the strong tone, which 
increases the strain ascribed to the preceding interval. 

The filling of an interval also influences its appreciation. 
With short times it is found that filled time seems longer 
than empty. If the time be longer, and one be permitted 
to read during one period and to do nothing during the other, 



354 FUNDAMENTALS OF PSYCHOLOGY 

the time spent reading seems shorter than the empty. The 
probable explanation of the latter difference is to be found 
in the fact that the empty time is really filled by noticing 
strains and other internal sensations, while, during the time 
occupied in reading, these strains are not present. One for- 
gets one's self and the passage of time in the interesting 
event. For longer times the filling seems to have a markedly 
different effect according as the time is regarded as it is being 
lived through, or as it is viewed in retrospect. While pass- 
ing, time in which one is occupied fully and during which 
much of importance is happening seems short, but when 
viewed in retrospect it seems long. Empty time, on the 
other hand, seems long in the passing but short in retrospect. 
During convalescence from a long illness the days drag 
interminably, but later the period seems inappreciable. 

Theories of Time Perception. — Attempts at a theory 
must take all of these facts into consideration and we must 
distinguish three ways of appreciating time. The first 
applies to the very short intervals, those under 600-7000-, 
below the indifference period. These, it has been suggested, 
are appreciated in terms of rhythm, since under that limit 
stimuli may be easily grouped into rhythmic wholes. The 
intervals are too short to be appreciated for themselves, 
they cannot be attended to, and so do not reach their full 
development. The second is effective for times between 
600 or 700 a- and two to four seconds; this is real time. It 
is apparently appreciated in terms of internal experiences, 
expectation processes, and other more definitely kineesthetic 
sensations. The length of the time is estimated in terms 
of the intensity of the strains. Short times give strains no 
chance to become strong, but their strength grows with the 
longer times. Strains of the muscles that accompany atten- 
tion, strains of expectation, even strains that come with 



PERCEPTION OF TIME 355 

respiration or with holding the breath, have been asserted 
to form the basis of the appreciation of the passage of time. 
The influence of the strength of the limiting stimuH would 
suggest the importance of the strains of attention in the 
estimation of time, as would the effect of the content of time. 
When the interval is empty, attention is more fully attracted 
to the passage of time, the strains are more pronounced, 
and the time seems longer. In the same way with longer 
intervals when there is nothing to do, the strains of expec- 
tation occupy consciousness and time seems long, while, 
when one is busy, attention is otherwise occupied and there 
is constant change, constant relaxation, the strains never 
rise to great intensities, and in consequence one is not im- 
pressed with the fact that time is passing. 

Times longer than from two to four seconds are appar- 
ently not directly experienced in the passing, but are only 
experienced as past. They fall outside of the present, are 
constituted for the most part by memories of past events 
revived in the present. They are estimated in terms of 
events that have happened in them, in terms of the occur- 
rences which fill them. In this they differ altogether from 
the shorter intervals that may be directly appreciated, and 
in consequence show the reverse illusions. Thus, times that 
are filled with interesting events seem long when they are 
looked back upon, although they seem short in passing; 
while times in which nothing happens seem short in retro- 
spect, although extremely long in their passage. It is this 
that explains the seeming decrease in the length of the days 
and weeks with advancing years. When one is young, all 
is interesting from its newness, and is always attended to; 
as time goes on, nearly everything becomes familiar, and 
receives less and less attention, and so less and less is remem- 
bered in retrospect. In general, times depend upon an 



356 FUNDAMENTALS OF PSYCHOLOGY 

appreciation of that which fills them. Very short times are 
apparently known from rhythm, longer times from the 
physiological processes, contractions and what not, that 
give the feeling of expectation and strain; while intervals 
longer than from two to four seconds, are appreciated 
from the events that happen in them. 

REFERENCES 

Ladd-Wood worth: Physiological Psychology, Chs. II, IV- V. 
Myers: Experimental Psychology, Chs. XX-XXIII. 
Titchener: Textbook, pp. 303-373. 
James: Principles, Vol. I, Ch. XV. 
Benussi: Psychologie der Zeitauffassung. 

The General Laws or Perception 

While space and time may be treated separately, since 
practically all perceptions imply them and they are con- 
sidered to have an existence independent of the objects 
found in them, certain laws of perception can be illustrated 
only by a study of the way in which separate objects are 
perceived. Speaking general^, it may be said that a per- 
cept is practically never merely a mass of bare sensations. 
The sensations at most provide a suggestion which is devel- 
oped in consciousness to make the object as we appreciate 
it. In optical illusions, certain elements are added, certain 
others are subtracted from the immediate group of sensa- 
tions, before we have the final percept. One is not aware 
of either the additions or the subtractions, much less of the 
sensations as immediately given before the modifications 
are made. This same process may be demonstrated to 
take place in practically every perception as we appreciate 
the nature of the real object. We are aware only of the 
final process, the object, but we can be sure from experi- 



READING AS PERCEPTION 357 

mental data that this is not merely a mass of sensations, 
but is the result of a complicated series of mental operations. 

Reading. — One of the best means of studying the 
various laws of perception is furnished by reading. Here 
the material is relatively simple and we have fairly full 
experimental evidence concerning the different phases of 
the process. Eirst it may be asserted that the word, not 
the letter, is the unit for reading This is demonstrated 
by the experiment on the distribution of attention. As 
was said in connection with attention, five or six letters is 
the maximum that can be distinguished on short exposure, 
but, when combined into words, twenty-five to thirty letters 
may be read at a single exposure of rs^ second. Evidently 
something must be added to what, is seen, or the word must 
be read as a whole rather than by single letters. There is 
evidence that both processes go on in some degree. Zeitler 
and the writer found that the reader was influenced by the 
general form of the word as determined by the relative 
positions of high and low letters, the length of the letters, 
etc. This is indicated again in print by the fact that one is 
much more Hkely to make mistakes and to have greater 
difficulty in making out the words if the upper parts of the 
words are cut off than if the lower be covered. 

On the other hand, the proofreader's illusion indicates 
that there is a constant tendency to supply letters or parts 
of letters from memory, to add centrally to peripherally 
aroused sensations. The writer found that if words were 
printed with letters omitted, with blurred letters, or with 
substitutions, and shown for a fifth of a second or less, 
they were read in a large proportion of the cases as if per- 
fect. The readers would occasionally give reports of the 
character of the letters, suppHed or transformed, which 
indicated that they belonged in the class of the centrally 



358 FUNDAMENTALS OF PSYCHOLOGY 

aroused sensations. The letters that were supplied or 
replaced were faint, had a pecuHar color, or seemed to be 
less permanent than the others. The Hkehhood of reading 
the misprinted word as if it were correctly printed was much 
increased if a word associated with the word to be shown 
was called before the exposure. This gave the right atti- 
tude or setting for seeing the word intended. That supple- 
menting is a factor even in the simplest reading is shown 
by the large number of misprints that are overlooked, some 
even by the most accurate proofreaders. The supplements 
in this case are not so permanent as are those in optical 
illusions. The latter persist for a considerable time in 
spite of all that one can do, and can be destroyed only by 
a long period of practice, but the proofreader's illusion 
vanishes when first one looks to make sure that a mistake 
has not been made. 

Reading Pauses. — One might deny that the conditions 
of ordinary reading, in which all the time that may be de- 
sired is given for looking, are similar to those in which the 
exposure is Hmited to a period too short to permit eye 
movements or wandering of attention. Recent studies of 
the mechanism of reading show, however, that the con- 
ditions are not markedly different. In the first place it 
has been found that, while reading, the eyes do not move 
steadily along the line with full time for the observation 
of all details, but make a few brief pauses. Photographs 
of the eyes as they move along the line show that they stop 
only from three to six times in a Kne of ordinary length, 
and then for but a very short time, approximately a fifth 
of a second. The number of stops varies greatly with the 
character of the material to be read. In reading a novel 
or similar Hght Hterature, the number is a minimum, and 
rises to a maximum with difficult material, in proofreading, 



READING AS PERCEPTION 359 

and for children who are learning to read. One really 
takes a series of snap shots of a line and pieces it together 
from them, rather than reading continuously. There can 
be apparently no reading while the eyes are in motion; 
they move so rapidly that nothing but a blur of after-images 
is left on the retina, and as this gives no knowledge, we have 
learned to pay no attention to it. 

Reading a Process of Supplementation. — All this leads 
to the conclusion that ordinary reading is a process of in- 
ferring unconsciously from the form of the words and a 
few letters what the word actually is. This process of in- 
ference is really nothing more than associating with the 
letters seen certain other letters frequently found with them, 
or of associating whole words with what little of the word is 
seen. Like all associations, these are under the control 
of the mental attitude, largely determined by the context 
and the knowledge that the reader can bring to the reading. 
The influence of the context can be seen in the different 
pronunciation and interpretation of a word composed of the 
same letters in different contexts. ' Lead' has one pronun- 
ciation when the subject of the sentence, another when 
it is the predicate, and we do not think of the one when 
the other is meant. The meaning is determined by 
the context, and what has gone before. Still more striking 
is the difference in pronunciation and interpretation that 
attaches to the same group of letters in different languages. 
Man has an entirely different sound and meaning in 
EngKsh and in German, and many other illustrations could 
be found. Suffice it to say that the sounds or ideas that 
are aroused depend very definitely upon the context. 

In reading it is evident, too, that the process of per- 
ceiving or of interpreting is not complete when the word 
as such has been seen. The process of translation into 



36o FUNDAMENTALS OF PSYCHOLOGY 

ideas follows. Sometimes one sees the words and follows 
them along with the sound of the spoken word, and thus has 
the ideas produced indirectly. Experiments show that to 
depend upon translation through internal speech is of no 
advantage and makes reading unnecessarily slow. More 
frequent in the adult is the immediate translation of the 
words as seen into images or ideas of some sort. As one 
reads in the most complete way, pictures or more abstract 
ideas accompany the reading. The clearer the style, 
the more immediately do the ideas follow upon the percep- 
tion of the words and the less prominent are the words, 
until with a maximum of clearness the words are largely 
neglected and the meaning alone comes to consciousness. 
This meaning may take the form of picturing the scenes 
described, of merely appreciating the abstract meaning, 
or of something intermediate. In any case, the outHnes of 
black and white that constitute the words start the associa- 
tion processes that lead to the ideas, and these associates 
are controlled by the wider setting and wider knowledge 
of the individual at the moment. The process is much 
Hke that in ordinary recall except that the stimuK are con- 
stantly received from the words. The revival of the earHer 
experiences is controlled by the laws of association and by 
the context in a degree that practically amounts in many 
cases to new construction. 

Understanding Spoken Language. — A similar process 
occurs in listening to another's speech. One does not 
appreciate how small is the proportion of a conversation 
that is heard distinctly until one attempts to follow a foreign 
language. Then it is seen that what must be perfectly 
clear to a native as a vehicle for ideas is really only a series 
of grunts and hisses with an occasional word clearly enun- 
ciated. Suggested by these, the words or the ideas are 



GENERAL LAWS OF PERCEPTION 361 

supplied through association. Bagley has shown that 
there is a process of filKng out the imperfections of sounds 
similar to the interpretation of letters in reading. The 
laws of supplementing are practically the same in the two 
cases. Something is given by the ear, this suggests words 
as one would speak them one's self or as they would look 
on the printed page. This is all that is really appreciated, 
and even when one hstens for the words, the imperfections 
are not noticed. When one hears a strange accent, the 
different deviations from the sounds one is accustomed to 
are overlooked, the man is assigned to his region of the 
country, and then no more attention is paid to the speech 
characteristics, unless one be interested in phonetics or 
have some other purpose in hearing the sounds, and in such 
cases the sense of what is being said is very Hkely to be 
lost. Artificial languages gradually take on the same char- 
acter. The separate elements become united into word 
units, and then acquire meaning, as do words themselves. 
This comes out particularly clearly in learning the tele- 
graphic language. There at first the sounds are heard as 
small groups and put together painstakingly and slowly 
into letters, but gradually words are heard as wholes and 
the meaning is suggested by a few words and omissions 
are filled in as in ordinary speech. Supplementing follows 
the same laws as in reading or Hstening. 

Resume of the General Laws of Perception. — If one 
may extend and generalize the laws of perception in read- 
ing and Hstening, it may be said that perception is primarily 
a process of arousing old experiences through association. 
These associations are controlled by both the subjective 
and the objective factors. Some few sensations always 
serve as the incentive to the perception process, but they 
serve as the incentive only. By them associations are 



362 FUNDAMENTALS OF PSYCHOLOGY 

aroused and, in that arousal all the experiences that have 
had any bearing on the process contribute their share. 
Some of the associations are determined through mere 
frequency of appearance with the original stimulus; others 
depend upon the attitude in which one is at the moment of 
looking or Hstening, and upon the inherent probabiKties 
of the situation. That one is not more often misled is due 
to the fact that objective situations repeat themselves so 
frequently, quite as frequently as do ideas. It is safe on 
the whole to assume that what we take as the sign of an 
old situation really accompanies that situation, for in the 
vast majority of cases the remainder of the elements are 
actually present. In practice it would take more trouble 
to stop to investigate than to take the chance and be wrong 
the few times that the new does not correspond to the old. 
It is striking, however, that in this case alone one does not 
distinguish between real sensations and the recalled images. 
Centrally and peripherally aroused sensations are combined 
in almost all perceptions, but one never can tell where 
the sensations stop and mental supplements begin. One 
seems as real as the other. 

The Influence of the Type in Perception. — In conclu- 
sion we may again emphasize the importance of type or 
concept in perception. This is a factor common to both 
perception and reasoning, — this is the tendency to replace 
a particular phase or aspect of an object by what has 
proved to be its more general or universal form. Usually 
one sees things as the previous experience convinces one 
they must be, rather than as they appear at the particular 
moment. Thus, one usually does not notice shadows as 
shadows, although they may aid much in the interpreta- 
tion of the form of the surface on which they fall. Simi- 
larly, one does not notice how indistinct are objects in the 



GENERAL LAWS OF PERCEPTION 363 

field of vision a little distance from the fixation point. 
What is seen is at once translated into an object of perfect 
form with full detail and distinctness, and all else serves as 
a mere background. Still more striking is the correction 
of the size of various objects. The standard size varies for 
the different objects. No matter how small or how large 
the image may be under a given set of circumstances, it is 
increased or decreased to a standard size. The image it- 
self is never seen, the fact that it has been changed in its 
size also is not noticed; the corrected standardized impres- 
sion at once replaces the retinal image. This standard we 
regard as the real object. 

Similar tendencies to replace mere sensation groups by 
concepts or by standardized objects may be seen any- 
where. The neglect of after-images, of contrast colors, the 
overlooking of imperfections in the media of the eye that 
can be seen clearly when one looks for them in a lamp 
flame, overlooking the retinal blood vessels in the visual 
field, — all of these omissions are quite as apparent as is 
the addition of quahties or characteristics not given in sen- 
sation. Equally striking are the changes in the forms of 
objects seen in perspective. As any article of furniture is 
looked at, the square corners are either increased to oblique 
angles or reduced to acute angles, according to the side 
from which one looks. A hundred students looking from 
different directions at the lecturer's reading desk will each 
receive a different impression, different in shape as well as 
in size, but the object is the same for all. The perception 
is changed in being seen, or a standard object is made to 
replace the various images, so that the final result is the 
same for each observer. This process of replacing the crude 
image by a standard object, an object that has been devel- 
oped by all of the individual's experiences, that has been 



364 FUNDAMENTALS OF PSYCHOLOGY 

gradually corrected by being seen under different condi- 
tions, by being handled, and even by making similar ob- 
jects or seeing them made, is practically universal. It is 
the developed standard object that always comes to con- 
sciousness, just as it is the corrected standard space that is 
always used as the basis of reference. To anticipate the 
discussion of a later problem, it may be said that we per- 
ceive concepts rather than sensations. As concepts that 
have developed in this way, we have not merely objects, 
but space and time and ssmilar abstractions which are in 
part components of the objects, in part to be regarded as 
independent. 

REFERENCES 

Huey: Psychology of Reading. 
Erdmann and Dodge: Ueber das Lesen. 
Gray: Individual Differences in Reading Ability. 
Pillsbury: The Role of the Type in Simple Mental Processes. 
Philosophical Review, Vol. XX, pp. 498 ff. 



CHAPTER XII 
MEMORY 

Memory is a topic that bulks very large in the discus- 
sions of daily life. In the complete form it may be defined 
as the recurrence of a group of experiences with knowledge 
of the time and the place in which they were experienced 
before. Memory is related to centrally aroused sensation 
in very much the same way that perception is related to 
sensation. It is a group of centrally excited sensations ac- 
cepted as representing some earlier seen object or previous 
event, as perception represents an object actually present. 

While the fundamentals of memory have been discussed, 
there is much of more particular application that remains 
to be considered — questions as to how the association 
processes may be used to the best advantage in the accu- 
mulation and application of knowledge. We may con- 
veniently divide memory into four part processes, — learn- 
ing, retention, recall, and recognition. Learning is no more 
than the formation of association; retention is the persist- 
ence of those associations; recall is the rearousal of old ex- 
perience; and recognition, the process of assigning the 
events to the time of their first appearance. Although as- 
sociation has been treated in general, we must consider 
here a large number of special rules and laws developed 
through experiment that throw new light on the nature 
and use of memory. To have the associations is not iden- 
tical with being able to use them. We shall weave to- 
gether the results obtained from experiments on the first 

36s 



366 FUNDAMENTALS OF PSYCHOLOGY 

three processes, before we consider recognition which in- 
volves certain relatively new principles. 

We may distinguish in the discussion of memory between 
the retention and recall of concrete objects and the recall 
of words or symbols. The process is different in the two 
cases because the symbols must be remembered directly, 
while the concrete objects are sometimes remembered di- 
rectly and sometimes translated into symbols which repre- 
sent them. The differences are sufficient to make it desir- 
able to treat the operations separately. The first we may 
call observational, the second, verbal memory. 

Memory or Objects and Events 

Observational Memory. — Observational memory de- 
rives its great practical importance from the fact that the 
evidence of the witness on the stand must depend for its 
accuracy upon this type. It is, of course, also the method 
that we use in describing the events of the day in conver- 
sation. Much, too, of the work of the observational sci- 
ences that is not recorded at once in notes depends upon 
the accuracy of this form of memory. We may say that 
the accuracy of recall depends: first, upon the way the 
material is seen at the time of the observation; secondly, 
upon the time that elapses between observation and re- 
port; and thirdly, upon the circumstances effective at the 
time of recall. What is seen depends upon the way the ob- 
server attends and upon the way he translates what he 
sees into words for retention and recall. Most individuals 
will notice objects, their form, position, and number first, 
and with an accuracy diminishing in that order. Colors 
are seldom noticed. Children are much more inaccurate 
than adults in all except possibly the observation of colors. 
Special practice in observation of any kind will greatly in- 



OBSERVATIONAL MEMORY 367 

crease the accuracy of observation. Practice is of some 
general value in calling attention to what is likely to be 
overlooked, and enabling the observer to attend especially 
to that. Accuracy is increased, too, by describing in words 
what is seen, and remembering the words rather than trust- 
ing to the images alone. Thus, if one will count the win- 
dows in a building as one looks, one will remember the 
number, but if one attempts to count them in the memory 
picture, the result is very likely to be wrong. 

Effect of Lapse of Time on Accuracy. — The effect of 
time is always in evidence. Dallenbach found that forget- 
ting took place rapidly at first and then more slowly, a 
law that holds for forgetting all types of material. Thus 
immediately after exposure, ten per cent errors were made; 
after five days this had increased to fourteen per cent; 
after fifteen days, to eighteen; and after forty-five days to 
twenty-two. The material used consisted of pictures, and 
the percentages were obtained by counting the number of 
objects in the picture and determining what per cent of 
them was recalled. It will be noticed that there was the 
same increase in the number of errors between one day and 
five as between five and fifteen, and fifteen and forty-five. 

Most errors of report that develop at the moment of re- 
call are due to the suggestion of objects that were not actu- 
ally seen. Any idea that presents itself is certain to sug- 
gest others, and this suggestion may lead the observer to 
think that it was actually present. This is an extension of 
the tendency for what is present to suggest at the moment 
of observation other things that are not really seen. Some- 
thing is definitely recalled, and this suggests something 
else that usually goes with it. This arousal of the idea 
may be accepted as constituting evidence that the object 
was really seen. Very striking is the influence of questions 



368 FUNDAMENTALS OF PSYCHOLOGY 

in increasing the number of errors. If the individual is 
told to tell all that he saw, he will make a report that is 
approximately ninety per cent correct. If he is questioned 
as straightforwardly as possible about the objects in the 
picture, the errors will increase so that he may have only 
seventy per cent correct. The advantage of questioning, 
which makes it essential that a witness be questioned in a 
court, is that many things he might report on will not sug- 
gest themselves without questions. Experiments show that 
the spontaneous report covers only twenty-five to forty per 
cent of the total number of objects present, while questions 
will increase this range to fifty or sixty-five per cent. What 
is lost in accuracy is gained in range. If leading questions 
are asked, particularly if they assume a wrong answer, the 
percentage of errors is increased much more. If one asks 
the color of the dog in the background, when no dog was 
present, about half of the individuals, even of superior in- 
telligence, will give some color. 

Rote Memory 

Experimental Methods. — Careful experiments on mem- 
ory were first made by Ebbinghaus in the eighties of the 
last century. To avoid the variation in degree of famiHar- 
ity and interest that might attach to words or any other 
material that has meaning, nonsense syllables were selected 
as the material to be learned. These were built up of con- 
sonants and vowels, two consonants with a vowel between. 
All combinations were excluded that chanced to make 
sense. Series were selected by lot from the mass of sylla- 
bles. Ebbinghaus wrote his series upon cards and then 
learned them by shuffling the cards. Most later workers 
have arranged the syllables upon some sort of revolving 
drum that exposes them at regular intervals and for defi- 



OBSERVATIONAL MEMORY 369 

nite times. They are said through regularly as they are 
exposed, until they can be repeated once or twice without 
mistake. Ebbinghaus measured the amount of effort in 
learning by the time required, but most later writers have 
chosen the number of repetitions as the measure. Two 
methods have been used to test the accuracy of the learn- 
ing or the amount of retention. The first, known as the 
method of relearning, was used by Ebbinghaus. It con- 
sisted in relearning the syllables, and assumed that the dif- 
ference between the time required for learning and for re- 
learning was a measure of the amount retained. This also 
measured the value of the method of learning used. In a 
second method, the method of paired associates developed 
by Miiller and Schumann and extensively used since, the 
syllables are learned in pairs and the amount retained is 
measured by showing the first member of each pair and 
asking the observer to supply the second. The percentage 
of correct answers indicates the amount retained. In 
many experiments, the time required for speaking the sec- 
ond syllable is measured. This serves as an indication of 
the strength of the association for individual pairs. The 
shorter the interval required, the stronger is the associa- 
tion. Each of these methods has given valuable results. 
They frequently supplement each other. The first meas- 
ures primarily the effective and latent memory of the 
whole; while the second permits a study of the effective 
connections between members of the pairs. One measures 
potential liability to recall; the other, the actual recall. 

The Laws of Learning 

Effect of Individual Repetitions. — One of the first pre- 
liminaries to the application of the method was to deter- 
mine the accuracy of the method itself. This involved first 



370 FUNDAMENTALS OF PSYCHOLOGY 

a determination of the effects produced by each repetition 
when a number of repetitions of the same series are made. 
Ebbinghaus tested this by repeating a series of syllables 
eight times and then finding the time required to relearn 
after twenty-four hours. He then repeated another series 
sixteen times and again relearned after the same interval. 
These experiments were repeated up to sixty-four repeti- 
tions of a series. Within these limits the amount retained 




Fig. qi . — Shows the increase in amount retained after twenty -four hours with 
the number of repetitions. The number of repetitions is plotted on the horizontal, 
the saving in seconds on the vertical axis. 

after twenty-four hours was directly proportional to the 
number of original repetitions. The last repetitions were no 
less effective than the first as measured by the amount re- 
tained. The diagram shows that the results, when plotted, 
lie almost in a straight line. Each repetition resulted 
in a saving' of about twelve seconds in the time required 
for relearning. This experiment also brings out the fact 
that learning is never absolutely complete or perfect. Per- 
fect learning at the moment will show defects in a few 



LAWS OF LEARNING 371 

hours or days, and the duration and accuracy of retention 
may be increased by repetitions much beyond the number 
required for the first perfect repetition. Each repetition 
will have the same effect as any other in the recall of the 
next day or of the next week. 

Relation between Length of Series and Number of 
Repetitions. — One of the more striking facts in connec- 
tion with learning is the great increase in the number of 
repetitions required for the longer series as compared with 
the shorter. It is found that an adult can remember from 
6 to 8 syllables or 11 to 13 numbers with a single repe 
tition, while Ebbinghaus found that it took 13 repetitions 
to learn a series of 10 syllables, 16.6 for 12, 30 for 16, 
44 for 24, 55 for 36, As the number of syllables in a se- 
ries increases, the number of repetitions required for 
learning it increases much more rapidly than in proportion 
to the increase in the number of syllables. The most 
striking increase is seen when the series is just longer than 
can be learned with one repetition. The number of sylla- 
bles that may be learned at a single reading to be repeated 
immediately has been called the memory span, or primary 
memory. This varies very markedly with age, with train- 
ing, and with the individual. It may be much increased 
by training at any age. According to Meumann, children 
from seven to nine can usually retain no more than two or 
three nonsense syllables, while the practised adult retains 
seven or eight. 

Effects of Grouping. — Learning a series not only forms 
associations between the contiguous syllables of the series, 
but knits the whole group together by associations formed 
between all of the syllables, however widely they may be 
separated. Ebbinghaus demonstrated this by learning 
certain series and then making up new series that should 



372 FUNDAMENTALS OF PSYCHOLOGY 

consist in part of the syllables of the primary ones. Thus, 
he would select syllables that had been separated by one 
syllable; and he found that the new series could be learned 
more easily than new syllables. He repeated the experi- 
ment, using syllables that had been separated by two, three, 
etc., syllables, up to those that had been separated in the 
original learning by as many as eight. He found in each 
case that a saving could be shown as compared with entirely 
new series. The results prove that associations are formed 
between the remote as well as the contiguous elements in 
a series. He also showed that associations are formed in 
both directions, backward as well as forward. Relearning 
a series backward saves about one-third of the time which 
is saved in relearning forward. It has also been shown that 
some connection is formed between the syllable and its 
position in the series. Syllables that are relearned in the 
same absolute position in a series are relearned more easily 
than when they take a new position. If the syllable is the 
third or the seventh in the series and is kept in third or 
seventh place, relearning is easier than if it is shifted to 
second or fifth place in the new series. All of these bonds 
of connection aid in making the series a unit. 

Effects of Rhythm. — Anything that serves to unite the 
syllables into minor units is of advantage in aiding learning. 
One of the means employed most frequently is rhythm. 
In repeating a series, the syllables are practically always 
combined in rhythmic units and given an accent. Learning 
in the natural rhythm is much easier than in a forced 
rhythm or without rhythm. The natural rhythm varies 
with the individual and probably also with the race, but 
whatever the rhythm used, some benefit is derived from it. 
The rhythmic unit also serves as a subordinate group 
within which associations are much stronger than between 



LAWS OF LEARNING 373 

contiguous syllables of different groups. Miiller demon- 
strated this by first learning series in trochaic rhythm 
and then forming from the syllables two sets of new sylla- 
bles. In one of these, the syllables were relearned in the 
same measures as in the original series; in the others, the 
syllables were contiguous but had belonged to different 
measures. The former showed a saving on relearning equiv- 
alent to five repetitions; the latter, no appreciable saving. 
This strong association within the group holds, not merely 
for the grouping in rhythmic units, but for any grouping. 
In learning nonsense syllables, practically no association is 
formed between the first syllable of one series and the last 
of the preceding. In common Hfe little connection is 
estabhshed between conversations on different subjects 
with different persons, even if one immediately succeeds 
the other. On the other hand, where material to be re- 
membered is broken up into smaller groups of a larger series, 
members of these groups are more closely associated for 
themselves, and learning the groups aids in learning the 
total series. This formation of subordinate groups is of 
great practical importance, and we shall have occasion to 
refer to it in connection with the development of meaning. 
Learning by Whole and Part. — One of the most im- 
portant practical laws for learning is that it is much easier 
to learn any selection if it is read as a whole instead of 
being learned by parts. This appHes to nonsense material 
under strict experimental conditions, and also to ordinary 
sense material, poems, etc. An investigation of this point 
was first undertaken by Miss Steffens under the direction 
of Professor Miiller. It consisted in comparing the time 
required for poems when learned as most people incline to 
learn them, a fine or a couplet at a time, with the time 
required when they are read through from beginning to end 



374 FUNDAMENTALS OF PSYCHOLOGY 

each time. The results indicate that, in practically every 
case, learning as a whole is more economical than learning 
in parts. The saving amounted to about ten per cent in 
Miss Steffens' experiments and held for children as well as 
for adults. Later investigations by Meumann showed that 
two stanzas required thirty-three repetitions by the part 
method, and only fourteen for the whole procedure. It 
should be said that unless some method of keeping the 
repetitions at a uniform rate be employed, the learner tends 
to lose interest and to repeat more slowly than he will if 
he is permitted to learn by parts. In some experiments 
this loss in rate almost offset the advantage gained from the 
need for fewer repetitions. With much practice, this loss 
may be overcome. The law has been demonstrated 
repeatedly. Not only does learning require fewer repeti- 
tions, but the material learned as a whole is much better 
retained than material learned in parts. There is also a 
fairly wide hmit of appHcation, as the whole method was 
found more economical by Pyle for selections that required 
as much as fifty minutes to read through. 

The reasons for the greater efficiency are threefold: 

1. They save much of the time ordinarily wasted 
in needless repetitions. In the part method, the first 
part of the selection is repeated more times than neces- 
sary through going back to connect the later learned 
with the earlier. There are several times as many 
repetitions of the first as of the later. 

2. Needless associations are made each time the 
reader goes back from the end of a Hne to its beginning. 
These take time and also may interfere with the forma- 
tion of the correct associates. 

3. As was said above, the connection of a word with 
its position in the selection is of some advantage in 



LAWS OF LEARNING 375 

learning, and the whole method always retains the 

absolute position of each word. 
Meumann and his pupils have shown that certain inter- 
mediate methods may improve on the strict method. Thus, 
it is frequently an advantage, after a number of repetitions 
of the whole, to repeat several times the parts of the selec- 
tion that offer special difficulties, and to learn them without 
making unnecessary repetitions of the easier portions. One 
can also obtain some of the advantages of the part method 
by making pauses at certain places, then in each case 
going on from that place after a few seconds. These pauses 
seem to attract particular attention to the words preceding 
and succeeding them, without the disadvantage of forming 
useless connections. In general, it is recommended that 
one read through the selection to be learned a few times as 
a whole; then, as fatigue comes on, introduce the pauses 
and, when it becomes evident that certain parts are offering 
special difficulties, make an extra number of repetitions 
of those parts until they are learned, then add a few repeti- 
tions of the whole to weld all together. 

Distributed Repetitions More Effective. — Another law 
that is equally well estabHshed, quite as important in prac- 
tice, and even more interesting, is the so-called law of divided 
repetitions. Briefly, this is that the more the repetitions 
are distributed over different days, the fewer the repetitions 
required and the more thoroughly the material is mastered. 
This conclusion was first carefully investigated by Jost. 
He tried learning nonsense syllables with twenty-four 
repetitions at one time, then similar series with eight 
repetitions per day for three days, then four for six days, 
and finally two a day for twelve days. It was found when 
they were tested by the method of paired associates twenty- 
four hours after the last repetition, that the fewer the repe- 



376 FUNDAMENTALS OF PSYCHOLOGY 

titions each day, the greater was the amount retained. 
Ebbinghaus had earlier compared greater numbers of repe- 
titions. On one occasion he read a series of twelve syllables 
68 times and found that twenty-four hours later he needed 
seven repetitions to relearn. Then he repeated another of 
the same length, lyi, 12, and 8i times, a total of 38, and 
found but five repetitions were needed for relearning twenty- 
four hours later. Still later Miss Perkins^ continued the 
extension of distributions, comparing accumulated repeti- 
tions of eight a day for two days, with four and two and one 
repetition per day, every other day, every third, and every 
fourth day. The results were tested after fourteen days 
and proved even more striking than those of the earher 
tests which were made after twenty-four hours. Eight 
repetitions a day for two days gave only from 9 to 17 per 
cent correct responses, and the larger number was obtained 
when three days were permitted to elapse between each 
series of eight repetitions. Four readings a day gave from 
25 to 41 per cent, with larger values for the wider distribu- 
tion of repetitions; two a day gave from 45 to 78 per cent, 
while a single repetition every day gave 79 per cent; a 
single repetition every other day, 72 per cent; ever)'- third 
day, 82 per cent, and every fourth day, 68 per cent. It 
would seem, then, that one repetition every second or third 
day gives a maximum value for learning. 

This law has been tested a number of times on children 
and adults, and even on the learning of animals, and always 
with the same results. Ulrich^ found that white rats could 
learn a maze with fewest repetitions if they were given one 
trial each third day. It holds also for sense material as 
well as for nonsense syllables. The explanation of the 

1 Perkins, British Journal of Psychology, Vol. 7, p. 253. 

2 Watson, Behavior, pp. 228 ff. 



LAWS OF LEARNING 377 

advantage of divided repetitions was suggested by some of 
the experiments of Jost. He found that, when he compared 
the number of repetitions required to develop completely 
two sets of associates of equal strength but of different ages, 
the older set required fewer repetitions than the newer. 
His method was to learn one series of syllables twenty-four 
hours before and then to make a few repetitions of another 
series a few hours before the test. The amount retained was 
tested by the method of paired associates. When three 
times as many correct associates could be given from the 
newer series, it required almost the same number of repeti- 
tions to bring each to the point where it could be said 
through without mistake. When the number of correct 
associates that could be given was approximately the same 
for both series, the older series could be fully learned much 
more easily than the more recent. His theory is that the 
associations continue to grow strong, to ' set,' for some 
time, perhaps for two or three days after they are first 
formed. That associations tend to increase in strength 
for a few days is known as 'Jost's Law.' This unearned 
increment that comes from the setting process makes it 
much easier to bring them back to full effectiveness some 
time after the learning, than if no time is permitted to 
elapse after the repetitions are first made. It is possible to 
connect this setting process with the continued activity, 
perseveration tendency, that constitutes the primary 
memory or immediate retention. This setting is one more 
expression of the inertia of the nervous system 

Several important practical deductions may readily be 
drawn from this law. Obviously, it connects well with 
the preceding law, since, if one is to read through each time, 
only short selections could be learned in any one day. 
Coupled with the advantage from divided repetitions, it 



378 FUNDAMENTALS OF PSYCHOLOGY 

gains full force, since, if the selection be not learned at the 
first sitting, it is an advantage to wait a day or two before 
proceeding to complete the learning. Again the bearing 
upon the famiHar topic of cramming is quite evident. What 
is repeated often at periods considerable distances apart is 
learned thoroughly, while accumulated repetitions in a brief 
period produce slight effect and one that quickly disappears. 
This is more certain from the fact that divided repetitions 
leave much more persistent effects than accumulated. In 
general, the more the repetitions are divided, up to one 
every third day, the more permanent will be the learn- 
ing. 

Rate of Repetitions. — Other factors that affect learning 
are the rate at which the material is read and the degree 
of activity or the degree of attention given it. The rate of 
repetition has been several times investigated with sHghtly 
different results. Ebbinghaus first asserted that the more 
rapid the rate, the quicker the learning. Ogden modified 
this by showing that learning was quickest when reading 
was at the fastest rate possible without too much effort. 
Part of this difference lay in the fact that Ebbinghaus used 
the time alone as a measure of effectiveness; Ogden em- 
ployed both time and the number of repetitions. Meu- 
mann, as a result of experience gained from many investiga- 
tions, concludes that the best rate varies with the individ- 
ual, the material to be learned, and the familiarity of the 
learner with the material. It is best to read relatively 
slowly at first when the subject matter is being understood, 
and more rapidly later, up to the point where the effort 
begins to distract. 

Active Repetitions More Effective than Passive. — The 
effects of the attention of the reader have been investigated 
numerically only in one respect, the advantages of passive 



LAWS OF LEARNING 379 

reading as compared with active repetition. Witasek 
made experiments to determine the best combination of 
reading with attempts to repeat. He found that the most 
satisfactory result was obtained when he read five times 
and then repeated fifteen times from memory. Skaggs ^ 
found it an advantage to intersperse a recitation between 
each reading rather than to have more than one of each in 
succession. It is evident that attempting to repeat from 
memory requires more effort and will hold attention much 
more than passive reading. It should be said, however, 
that repeating material that has lost its freshness in an 
abstracted state, practically without attention, will give 
rise to learning in a much shorter time than one would 
think, although it is of course not so effective as repetition 
with full attention. Still another factor that plays an 
important part in learning is the intention to recall. Meu- 
mann and others found a saving of 50 per cent or more if 
series were repeated with the expectation of being tested 
on them later, as compared with similar series that were 
learned without knowing that the learning was to be 
tested. Sanford^ found almost no learning to result from 
the daily reading of the morning service, without intention 
of recall. 

Associative Inhibition. — An important factor in pre- 
venting learning is the presence of other earlier formed 
associations with the syllables to be learned. Miiller and 
Schumann found that, if two associates are made with the 
same syllable, they interfere with each other, and the 
second will be learned with greater difficulty. They 
demonstrated this by learning a series of syllables a, d, g, 

1 Skaggs, Journal of Experimental Psychology, Vol. 3, p. 424. Cf. Gates: 
Recitation as a Factor in Memorizing. Archives of Psy., No. 40. 

2 Studies in Experimental Psychology. Titchener Volume, p. 5. 



38o FUNDAMENTALS OF PSYCHOLOGY 

etc., first with h, e, h, etc., and then later a with c, d with/, g 
withy, etc. It was found that it took considerably longer 
to learn the series of syllables when other syllables had 
already been connected with them than when learned for 
the first time. In the experiments, the syllables to be re- 
learned were interspersed irregularly, so that the association 
with the old positions and with syllables, that were near 
but not contiguous in the first connections, should not aid 
in the relearning. In practical life this means that when 
one thing has been learned with another, it will require 
a longer time to learn it with a second than if it had not 
been learned with the first. If a mistake has been made, 
it will take longer to correct it than it would to have learned 
it correctly in the first place. But where several things are 
to be learned in the same connection, it is found that 
inhibition ceases to be effective if the first is thoroughly 
learned before the second is begun. In fact, in that case 
there is apparently some saving, since the familiarity with 
the old saves some work in learning the new. This inter- 
ference of earlier formed associates with the formation of 
new ones is known as ' associative inhibition.' 



Retention and Forgetting 

The Rate of Forgetting. — The investigations of the re- 
tention of associations bear largely upon the rate of the 
disappearance of associations with time. There is a gen- 
eral tendency toward the unlocking of associations that 
begins at the moment of reading or a few moments later, 
and goes on indefinitely. Two long studies have been 
made of this topic, one by Ebbinghaus, the other by 
Radossawljewitsch. Their results may be compared in 
the table on the following page. 



LAWS OF FORGETTING 



381 





Per Cent Forgotten 




E 


R 


5 min 

20 min 

ihr. . . . . . . . 

8 hr. 45 min 

8hr 

1 day 

2 days 

6 days 

30 days 

120 days 


41.8 
SS-8 
64.2 

66.3 
72.2 
74.6 
78.9 


2-S 
II.4 

29-3 

52.6 
32.2 
39-1 
SO- 7 
79.8 
97-2 



The main difference is to be seen in the fact that Ebbing- 
haus found a larger percentage forgotten in the shorter 
periods. Both indicate a relatively rapid forgetting at 



5- 



/ 



/ 



— T— 

24 



1 



48 



144 



Fig. 92. — Analysis of the curve of forgetting to show possible cooperation of 
perseveration and association. The full line shows the course of forgetting after 
Ebbinghaus, the dotted line the conjectured decrease in the primary memory (per- 
severation) and the dashes the initial increase in the strength of association due to 
perseveration. 

first, and a relatively slow rate in the longer intervals. 
It should be remembered that nonsense syllables were 
used and that these are forgotten much more quickly than 
sense material. Sense material shows a somewhat similar 



382 FUNDAMENTALS OF PSYCHOLOGY 

curve but a much slower rate. The comparative rapidity 
of forgetting during the first few days suggested to Mliller 
that it was very likely that two factors should be taken 
into consideration; first, perseveration, or the memory 
after-image, which diminishes very rapidly and may be 
regarded as disappearing in the first two days or so, and, 
second, the associative tendency, which in accordance 
with Jost's law is to be conceived as increasing in strength 
for two days or more and then decreasing in strength very 
slowly. For most purposes the increase in the strength 
of the associative tendency is masked in the total curve 
by the rapid decrease of the perseverative tendency, but 
later the decrease in the strength of association is repre- 
sented by the curve of forgetting (Fig. 92). 

Retroactive Inhibition. — The one factor which seems to 
influence the retention or forgetting process is the series of 
events which take place in the few minutes immediately 
following learning. Miiller and Schumann were the first 
to observe that learning a second series of syllables im- 
mediately after the first decreased the likelihood of recalling 
the first. The interval within which the second may inter- 
fere with retention is about six minutes. The degree of 
interference seems to increase with the similarity of con- 
tent between the two series, but any mental work will be 
injurious within that period. The effect is greater when 
the individual is fatigued or in periods of lessened effective- 
ness, and is also greater when the first has not been too 
well learned. The explanation of the phenomenon is that 
the associations are being strengthened during the period 
of perseveration that immediately follows the learning. 
If attention is turned to anything else, the perseveration 
is interfered with, and so associations are less likely to be 
formed. Memories may also be prevented from ' setting ' 



LAWS OF FORGETTING 383 

by a physical or mental shock of sufficient severity. Fre- 
quently after an accident one remembers nothing of the 
events that immediately preceded the accident and nothing 
of the injury itself. The shock of the injury will wipe out 
the effects of the preceding events. This retroactive in- 
hibition is another instance in which we have evidence of 
the influence of the perseveration through the continuing 
activity of the cortical cells after the stimulation ceases. 

Is Forgetting ever Complete? — It is evident from these 
studies that associations persist when there is little imme- 
diate awareness of them, when one cannot bring them back 
by an associate closely connected with them; when they 
can be detected only from the fact that they may be re- 
learned more easily than if they had not previously been 
learned. This fact has given rise to much discussion as to 
whether anything is ever forgotten. The discussion arose 
originally from the fact that occasionally long-forgotten 
events from a remote past are recalled. Coleridge cites 
the case of a girl, a servant in the house of a pastor who 
was accustomed to walk up and down a passageway near 
the kitchen where she was employed, reciting passages 
from Greek, Latin, and Hebrew authors. Some years 
later in a delirium of fever she was heard to recite strange 
words that convinced her attendants that she was possessed 
of a devil. The physician wrote them down and traced 
them to works in the possession of the old pastor, now 
some years dead. If the case is to be accepted, memories 
that never were consciously developed, and which should 
have been forgotten if they ever had been developed, may 
still be lying dormant in the nervous system. Numerous 
other cases may be cited of the return of experiences long 
forgotten, usually in case of disease, under hypnosis, or in 
similar abnormal conditions. These cannot be taken to 



384 FUNDAMENTALS OF PSYCHOLOGY 

prove the thesis for which they are adduced, but they may 
serve to reenforce the statement that experiences leave 
their effect for some time after they can no longer be re- 
called through associations of ordinary strength. Not 
improbably the nervous system never altogether loses 
some trace of them. This fact is of more importance in 
explaining recognition, the control of behef, and similar 
processes, in understanding which we must appeal to the 
effect of experiences not definitely conscious at the moment, 
than as a contribution to the understanding of retention 
and recall. Memories constantly grow weaker at a rate 
that depends upon their meaning and interest, and gradu- 
ally, if not refreshed, reach the stage at which they cannot 
be revived. 

Recall 

Recall, as was seen in Chapter VIII, is always through 
association under the control of the wider purpose of the 
moment and of other less conscious factors that constitute 
the mental attitude or context. To recall any old event 
it is necessary to have some idea which is in some way 
connected with that event or has some element in common 
with it. If we assume the possession of a definite memory 
with a large number of connections, some one of the con- 
nections must become conscious before the memory itself 
will make its appearance. Usually the desire to remember 
is either itself an associate of the memory desired or both 
are connected with a common idea. Thus, when one is 
asked a question in an examination, the question has been 
connected with the answer and serves or should serve to 
recall it. The course of the association is determined by 
the setting, the context of the question is supplied by the 
subject in which the examination is held. In practical life 



RECALL 385 

the occasion for the recall is a need for the bit of knowledge. 
A face presents itself and one knows that the name will be 
needed when it becomes necessary to make an introduction ; 
or one is reading of the size of a ship in metres, and wonders 
how long it is in feet, and must recall the table of equiva- 
lents. In each case there is always something that makes 
it desirable to know the thing to be recalled, and this has 
also been associated with the fact. Not all associates of an 
idea are actually recalled. The reason for this is usually 
that the right context is lacking. One may read of the 
length of the ship in comparison with other ships whose 
lengths are also given in metres, and as relative size is all 
that is necessary, the thought of the equivalent does not 
occur to one. The mental attitude or need of the moment 
always plays a predominant part. 

Reproductive Inhibition. — Interesting, if relatively un- 
usual, are the instances in which one has occasion for a 
fact, is sure that it is known, perhaps well known, but in 
which one cannot recall it. One may be asked the name of a 
famous painter, and find to one's astonishment that it cannot 
be recalled, torture one's memory for it as one may. Fre- 
quently after the occasion for it has passed, it will come 
back without the least difhculty, often when thinking of 
something entirely different. Phenomena of this sort seem 
to fall under the head of reproductive inhibition that was 
established by Miiller and Schumann and confirmed by 
Shepard and Vogelsonger. It was found that, when two 
syllables were learned at different times in connection with 
one single first syllable, there was not merely an obstruction 
to the formation of the second association through the earlier 
formation of the first, but also an inhibition of the recall 
of both when the common first member of each pair 
was shown. The time required for the recall of either is 



386 FUNDAMENTALS OF PSYCHOLOGY 

much increased, while the percentage of times that either 
will be recalled correctly is correspondingly decreased. It 
seems probable that something hke this happens in the 
moments of blocked recall of familiar facts. The associa- 
tions must be present, as is shown by the later recall; but 
apparently too many associates strive for entrance, and 
each, through some neural interference, blocks the way of 
the other. It should be added that there is some evi- 
dence, obtained by Bair^ in his experiments on learning 
typewriting, that when a series of associates has been fully 
learned — when one keyboard of the typewriter has been 
thoroughly mastered — another can be learned in less 
time and there is no interference between them on recall. 
Were this not true, there would always be interference. A 
blocking of recall would be much more frequent than we 
find it, since practically every bit of knowledge has many 
associates that might be recalled. The effect of the purpose 
or attitude is usually sufficient to prevent inhibition. When 
the context favors one associate much more than another, 
the way is cleared for it and all others are kept from inter- 
fering. Interference comes when the associations are not 
fully formed, are relatively weak, or no strong purpose is 
dominant. 

Learning and retention depend upon the formation of 
associations and the degree in which they persist, and recall 
is Hkewise through the connections that are formed in 
learning. It, too, is largely a mechanical process, dependent 
upon the relative strength of the associations, guided only 
by the context and the purpose of the moment. The laws 
that have been given are statements of the conditions under 
which the associations may be formed with greatest strength 

^ J. H. Bair, The Practice Curve, Psychological Rev. Mon. Supplements 
No. 19. 



RECOGNITION 387 

and in the shortest time, together with an enumeration of 
the factors that influence retention and the course of for- 
getting, and the laws of recall. These conclusions are of 
value in practice, since the laws hold not only under experi- 
mental conditions and for nonsense syllables, but also for 
sense material under conditions of ordinary learning. But 
in addition to these laws which apply to the raw materials 
of memory, the fact that memory ordinarily deals with 
things as real introduces the elements of meaning and logical 
interconnection, two factors which are important in deter- 
mining the ease of learning and recall and the use to be made 
of ideas. The most important influence of meaning, in 
fact what first gives meaning to groups of centrally excited 
sensations, is recognition. By recognition we mean that 
the idea has been accepted and given a place in the experi- 
ence of the individual. It is this in large measure that trans- 
forms the raw materials into ideas, into objects and events 
that have a real relation to the past life of the individual and 
to his knowledge. 

Recognition 

It was said in an earlier chapter that practically all 
mental processes follow the pattern of action in consisting 
of two distinct parts, one like the 'trial and error' learning 
of a new movement which induces the state, and the other 
a process which examines the state and either accepts or 
rejects it. Recafl provides the material in memory, recog- 
nition is the process of accepting or rejecting. It affirms 
or denies in part by assigning a date, — by referring the 
experience to the time and place of its original appearance. 
This is in itself a warrant for the truth of the recalled pro- 
cess. Thus in an examination many ideas may be suggested 
one after another, as the answer to a question of fact. If 



388 FUNDAMENTALS OF PSYCHOLOGY 

questioned, it is usually not until the idea can be assigned to 
a particular book or to a particular lecture that it will be 
accepted as sufficiently assured to put down. Recall must 
be tested and confirmed by recognition before memory is 
complete. 

The Process of Recognition. — Recognition applies to 
objects as well as to ideas or memories, and may be studied 
equally well with one or the other. When one sees a person 
one must decide whether he is an acquaintance or a stranger, 
before one speaks; and if he proves to be an acquaintance 
and he approaches, it is convenient to know the name and 
where he was seen before. The process of recognition may 
in itself be nothing more than the arousal by association 
of his name or of the place where he was last seen, or of the 
topic discussed with him at the last meeting. When these 
associates present themselves one is said to recognize. 
The exphcitness of the recognition depends upon the 
definiteness of the associations that come to cluster about 
the face. Memories are recognized in much the same way. 
When the idea is recalled, secondary ideas are aroused 
which give the first a setting and a warrant. 

An objective study of the phenomena of recognition adds 
much that must be considered in any theory. As compared 
with recall, recognition is as a rule easier and induced by 
fewer repetitions. A student will frequently recognize an 
answer when given by another in a recitation after he has 
himself failed. It is easier to learn nonsense syllables to 
the point where they may be recognized when shown than to 
the point where they may be repeated. On the other hand, 
one frequently finds in pathological cases that recognition 
is disturbed while recall is still almost unimpaired. This 
is seen in psychasthenia, and in certain cases of insanity, 
particularly in Korsakoff's disease. The psychasthenic at 



RECOGNITION 389 

times will find everything strange, at other times will 
recognize objects and people that have never been seen 
before. Everything seems strangely famihar to the patient. 
It seems that recognition is a rather more certain process 
than recall in the normal individual, but is more easily 
disturbed in the abnormal ; in fact it is often the first process 
to be disturbed in mental deterioration. It is also less 
affected by work performed after the learning — by retro- 
active inhibition — than is recall. In some ways, then, it 
seems more easy to induce recognition than recall, but at 
the same time recognition is more deHcate as measured by 
the susceptibihty to impairment by disease, but is not so 
readily disturbed by mental work immediately following. 

Experimental Studies of Recognition. — Experiments 
were early made and have been frequently repeated on the 
effects of the passage of time upon the accuracy of recog- 
nition. The results fall into two distinct classes which may 
be represented by two of the earhest workers, Wolfe and 
Lehmann. Both sought to determine the influence of the 
lapse of time upon the accuracy of recognition. Wolfe^ 
worked with tones which could be made to differ by as Httle 
as four vibrations, and had a number of tones at his com- 
mand, so that they could not be readily referred to a class 
or given a distinguishing name. He found that capacity to 
recognize diminished with the passage of time, at almost the 
same rate as the abiHty to recall. His curve showed the 
same form as Ebbinghaus' curve of forgetting; recognition 
fell off rapidly at first and much more slowly later. Leh- 
mann^ used gray papers of different shades. At first he 
used five shades. His subjects at once arranged these in a 
series and gave a definite name to each. His results showed 

^ Wolfe, Philosophische Studien, Vol. 3, p. 534. 
2 Lehmann, Phil. Stud., Vol. 5, p. 96. 



390 FUNDAMENTALS OF PSYCHOLOGY 

almost no tendency to diminution of accuracy with the 
passage of time. At first the judgments increased sHghtly 
in accuracy and then declined sHghtly, but there was no 
approach to the logarithmic curve obtained by Ebbinghaus, 
When Lehmann introduced nine shades, these were given 
numbers from one to nine, and the curve retained the same 
form. Later investigations by Angell and Hayward^ and 
by Hayden^ under approximately the same conditions 
have given results similar to Lehmann's. The difference 
in the results obtained by Wolfe and the others may be 
attributed to the degree in which the material makes possi- 
ble the association of a word or other famihar symbol. 
Where no such symbol may attach, recognition is difficult, 
and abihty to recognize vanishes very quickly. When the 
symbol may be applied, recognition is immediate and per- 
sists for some time with no appreciable diminution. Back 
of the assignment of the name or number is the develop- 
ment of a definite image or notion of the different impres- 
sions to be recognized that shall make it stand out for itself 
and so shall constitute a fixed standard. 

This difference between the results obtained by Wolfe 
and those obtained by the others is similar to the difference 
between results with nonsense and sense material. A 
number of recent experiments by HolHngworth, Miss 
Mulhall, Strong, and others, showed the same difference in 
ease of recognition between material that has and that 
which has not meaning. They found in the first place that 
recognition was much more certain and persisted longer than 
ordinary recall. It was from two to three times as accurate 
as recall when advertisements, pictures, words, or other 
sense material was used. But with nonsense syllables, 

1 Angell and Hayward, American Journal of Psychology, Vol. ii, p. 67. 

2 Hayden, American Journal of Psychology, Vol. 17, p. 497. 



RECOGNITION 391 

recognition had very little if any advantage over recall. 
If we apply this to our other problem, it is evident that 
recognition of meaningful material has a very great advan- 
tage over recognition of nonsense material. In the one case 
the shades of gray could be immediately connected with 
words that had either a definite meaning acquired long 
before the experiments were begun, or that could be 
quickly developed for the few shades used. One association 
alone needed to be formed in order to assure recognition 
in each experiment. Recognition itself required no more 
than a decision whether the shade offered did or did not 
correspond to the standard required. In Wolfe's experi- 
ments, no standards were present at the beginning and none 
could be readily developed because of the great number of 
tones used, and the shght differences in pitch that were 
available. Here one dealt with bare association processes 
formed during the experiments between sensations, neither 
of which had a meaning of its own. All the preparation for 
recognition must be made during the experiment, while in 
the experiments with meaningful material, most of the 
preparation was completed before the experiments were 
begun. Meaning, then, contributes much to the ease and 
persistence of recognition. 

Forms of Recognition. — Investigators have classified 
the different varieties of recognition. 

We may regard as complete recognition a feeling of 
assurance as to the place where the object was seen 
before, and a recall of all the circumstances of that 
earlier experience. This is called definite as opposed 
to indefinite recognition. 

In the latter case, one is aware that the thing is 
famihar but can assign no definite place to it. Many 
faces are familiar which arouse no name, and cannot 



392 FUNDAMENTALS OF PSYCHOLOGY 

even be referred to a specific time or place. This 
indefinite recognition is ordinarily due to slight 
familiarity. 

At the other extreme, things which are very familiar 
are also recognized, but, because of their great famil- 
iarity, are referred to no definite place. Here the 
recognition is taken for granted. This happens with 
the furniture of a well-known room, with intimate 
friends, and with events that are frequently recalled. 
It is an impHcit as opposed to an expKcit recognition. 
The objects are treated as if known, arouse a feeling 
that is different from that aroused by strange objects, 
but are seldom referred to earher times or even named. 
Still another distinction must be drawn with reference to 
the way in which recognition takes place. In certain 
instances one can see how the recognition goes on. A 
hauntingly familiar memory makes its appearance, but it 
has no connections and can be given no place. Gradually, 
as one broods over it, other things are called up by it. Then 
suddenly an associate, itself famiHar, is added to it, and 
recognition is complete. This may be called mediate 
recognition, as opposed to the immediate recognition 
which is much more usual. As will be seen, all of these 
types have common laws. Those mentioned later are 
reductions from the complete form. 

The Association Theory of Recognition. — Theories of 
recognition are very numerous and in some degree con- 
fhcting. One has been already indicated, the placing of 
the unknown through association with the known. This 
can be traced empirically very frequently. One hears the 
title of a book; it sounds famihar, but can be given no 
place. Gradually, ideas cluster about it until it is placed 
as a novel by such an author, read on the boat two years 



RECOGNITION 393 

ago; or it may be remembered as the book that was recom- 
mended by Jones but which has not been read. Similarly 
with the recognition of objects. This bit of crystal at first 
seems to be absolutely unknown; then a background grows 
up about it; you remember where it came from; that sup- 
plies the name and the purpose for which you obtained it, 
and the whole recognition is complete. The association 
theory assumes that all recognition is of this type, and that 
in the cases in which the recognition is indefinite the asso- 
ciates are present and have their effect, although they are 
overlooked or do not come to full consciousness. They 
nevertheless provide the mark of familiarity, give a color 
to consciousness that is accepted as a warrant for the behef 
that the idea or object has been experienced before. 

Unnoticed Associates May Induce Recognition. — Even 
in immediate recognition the associations give the quaUty of 
familiarity. Probably the feeHng of familiarity is due in 
the case of these very frequently repeated objects and events 
to partially open association paths that give recognition 
without any definite recall of the associated events. When 
the object is famihar but cannot be definitely placed, it is 
probable that there are also partially open association paths, 
but that they do not lead to the meaningful object or to the 
fixed landmark. The feeHng is present with nothing to fix 
the experience. Similarly, in certain cases in which the 
recognition is false, when one sees an individual who seems 
famihar but on speaking finds that he is not an acquaint- 
ance, it is probable that something in the person suggests 
another or calls up associates that are misplaced. Here the 
associates give the feehng without even warrant in fact. 
In short, partially open association paths give the feeHng 
of familiarity when recognition is not complete and even 
when the recognition is not objectively true. 



394 FUNDAMENTALS OF PSYCHOLOGY 

The Motor Theory. — Another theory with many adher- 
ents is that the feeUng of famiharity comes from sHght 
movements awakened by the stimulus or image. This is 
approximately the same theory as the other, except that 
the processes aroused are first motor, then sensory. The 
idea arouses some habitual movement, sHght or more in- 
tense, and this constitutes the basis of the assurance that the 
object has been seen before. The movements themselves 
are not recognized, but because of their arousal the famil- 
iarity attaches at once to the object. The best instance of 
this is to be found in the feeUng of ' at homeness ' that 
comes with the use of an old tool or instrument when one 
comes back to it after a period, as compared with the feehng 
of a strange one, even if it is of the same pattern. The 
habits that have been developed in its use are suited to it, 
and the pleasant feehng of familiarity results. 

The Feeling Theory of Recognition. — Another group of 
theories starts with the assumption that recognition is an 
immediate experience that cannot be analyzed or explained, 
but must either be accepted as a given fact or be speculated 
about in general terms. The more definite of these theories 
asserts that recognition comes because of the pleasure 
which attaches to the familiar experience as compared with 
the unpleasantness or neutral quahty of the unknown. 
The pleasure is explained as the result of an instinct. The 
known is pleasant, since one always makes an immediate 
response to it. If harmful, one can avoid it immediately; 
if beneficial, it is pleasant in and of itself. The objection 
to the theory is based primarily on fact. Not all cases of 
recognition are pleasant, certainly not all pleasant things 
are familiar. Another theory in this group asserts that 
famiharity is an immediate conscious experience, even more 
primary than either sensation or association. This theory 



RECOGNITION 395 

represents a possible interpretation, if all others fail. The 
same objections hold against it as those raised against na- 
tivism in space. It gives up the problem without attempt- 
ing an explanation. 

The Advantages of the Association Theory. — The evi- 
dence so far accumulated favors the association theory in 
some form. Indirect recognition can be traced to associa- 
tions. In direct or immediate recognition, we cannot de- 
tect associations exphcitly. Nevertheless, three facts in- 
dicate that they must be present, (i) Things that have 
many associates are readily recognized, while nonsense ma- 
terial — that is, material without associates — is recognized 
with difficulty, is recognized no more easily than it is re- 
membered. Recognition is aided also by two of the factors 
that aid association. (2) Meyer showed that recognition 
of nonsense syllables was more accurate when a syllable 
with which it had previously been associated was shown, 
just before the syllable to be recognized was presented. 
(3) It has been proven, too, that recognition is quicker and 
more accurate if the individual is in the proper attitude 
toward the object to be recognized just before it is shown. 
Just as in everyday life, if one meet an old acquaintance, 
when one has been thinking about the place where he was 
known, one is very much more Hkely to recognize him than 
if he appears without any preparation. These four facts 
together indicate that association and recognition are very 
closely related. Recognition always comes when associates 
are aroused, and where associates are not overtly present, 
experiments indicate that conditions which favor the for- 
mation of associates or recall by association also favor 
recognition. 

Meaning and Recognition. — In any statement of the 
association theory of recognition, it is taken for granted 



396 FUNDAMENTALS OF PSYCHOLOGY 

that the associates must be themselves famihar or the 
process will not be complete. Sometimes several links are 
necessary before a familiar associate presents itself. The 
familiarity that attaches in turn to the associates effective 
for recognition and also to the objects recognized immedi- 
ately is itself due to associates. The difference between the 
mediate and the immediate is another expression of the 
difference between the two sorts of recognition that distin- 
guished the methods used by Wolfe and by Lehmann. In 
Lehmann's form the new is related to some established 
type, to something that has been used so frequently and 
recalled so often that it has become firmly established and 
thoroughly famihar. These are accepted at once and with- 
out question. They are the types that we found necessary 
to explain perception, and are also the concepts that play 
an essential part in reasoning. Probably these fixed points 
of reference for our knowledge are also established and re- 
ceive recognition through the numerous associates that 
they tend to arouse but which do not become explicit. 
Your own name, to take an extreme case, is established 
more firmly in your mind than the name of another, be- 
cause of the number of times it has been associated with 
yourself and with other experiences. Certain events be- 
come landmarks in all memory and may be used as points 
of reference because of the number of associates that have 
been made with them, and through their frequent recall in 
different connections. When an event that is at first un- 
placed can be attached to one of these firmly established 
incidents, it at once takes on something of its famiharity, 
in the same way that assignment of the name was all that 
was necessary in Lehmann's experiments to constitute 
recognition of the shade. 
Recognition and Cognition. — Recognition is largely 



MEANING AN AID TO MEMORY 397 

aided by the types that were found so important in per- 
ception, and also by meaning, a process fundamental to 
thinking of all sorts. The part played by the type and 
by meaning may be seen more clearly in the more general- 
ized form, cognition. Here objects are referred to classes 
rather than to particular times or places. It is more fre- 
quent than recognition. We are constantly referring all 
objects that come under our notice to a class. Natural 
objects are named, tools related to their uses, people are 
assigned to different races or classes when they are not 
acquaintances. This process of cognition differs from rec- 
ognition only in that there is no reference to the earlier 
experience of the individual, no awareness that the thing has 
ever before been seen. Except for determining ownership 
of objects and for our relations with people, it is seldom 
that we need to do more than cognize. Cognition differs 
from recognition solely in that the reference is to some 
class only, some type of objects, with no reference to per- 
sonal knowledge. The process involves the same factors; 
a general notion always serves as the point of attachment, 
but this has a more or less marked series of associations 
that irradiate from it to give appreciation of its use, or of 
its special characteristics. In almost every respect it is like 
the type or concept which we saw to be evoked in percep- 
tion, and which constitutes what we accept as the real ob- 
ject. Cognition is a reference of the particular object or 
memory image to a similar typical object or class. Mem- 
ory is like perception in that it deals with real objects or 
concepts, rather than with mere centrally aroused sensations. 

Meaning an Aid to Memory 

Meaning in Learning. — Meaning is not only a factor in 
making recognition possible but is also an important fac- 



398 FUNDAMENTALS OF PSYCHOLOGY 

tor in all learning. The meaning that the material to be 
learned has for the individual determines in very large 
degree how quickly it may be learned and how long it shall 
be retained. The difference in the amount of time re- 
quired for learning and the degree of retention between 
sense and nonsense material is very striking. This may be 
seen both in primary memory and in learning long series. 
Ebbinghaus found that school children could give only five 
of seven nonsense syllables, while of a sentence of 38 words 
containing seventeen separate ideas, they could remember 
fifteen of the ideas. For himself he found that with the 
same number of repetitions he could remember eight or 
nine times as great a quantity of simple poetry as of non- 
sense syllables. Meumann obtained slightly smaller values, 
7-9 nonsense syllables, 13 words or numbers, 20 words of 
a poem, and 24 of philosophical prose. 

Meaning not only aids in learning but also assures a 
greater persistence of the material that is learned. The 
material learned is much less readily forgotten. Ebbing- 
haus demonstrated the fact for rote memory of verse. In 
some of his earlier experiments he used a translation of 
Byron's "Don Juan." After twenty-two years, he found 
that he could detect a saving of 7 per cent in the time re- 
quired for relearning stanzas as compared with learning 
new stanzas. After seventeen years there was a saving of 
20 per cent in relearning stanzas which had originally been 
learned on four successive days. This is to be compared 
with a saving of 20 per cent for nonsense syllables at the 
end of thirty days. The retention of ideas is still more 
complete. General principles, or even interesting events, 
are frequently recalled after the greater part of a lifetime. 
Here, however, there is usually repetition or recall in the 
intervening years. 



MEANING AN AID TO MEMORY 399 

Meaning Due to Grouping and to Reference to Systems 
of Experiences. — Two reasons may be found for the 
greater ease of learning meaningful material. First, that 
to gain meaning the different partial experiences must be 
grouped about a single centre, must be combined into 
units, and these units are then remembered practically as 
single elements. In some recent investigations of a light- 
ning calculator, Dr. Ruckle, G. E. Miiller found that an 
essential element of his ability to make calculations very 
quickly was his capacity for remembering figures, and that 
this in turn was due to an ability to unite the figures into 
small groups. Riickle could retain and repeat in any order 
forty-nine digits. He saw them arranged in seven columns 
of seven digits each. The seven series seemed to count for 
him as seven single units. A second element in acquiring 
meaning, well illustrated by this same investigation, is the 
attachment of the thing to be remembered to elements of 
experience already firmly fixed, — an interpretation in the 
light of old knowledge. Ruckle related many of the num- 
bers that he could remember to combinations of numbers 
with which he was already familiar. Thus he remembered 
451,697, because it was made up of the multiples of 
two prime numbers: 451 = 11X41,697 = 17X41. Six hun- 
dred and twenty-four was easy, since it is the square of 25 
minus i.^ With a large acquaintance with numbers, learn- 
ing new ones was relatively easy. All material that has 
meaning has these two qualities. It is combined into rela- 
tively small groups. These groups are used over and over 
again until they constitute practically a unit and they are 
learned in different connections until firmly established 
and then can be recalled by many other experiences. 

When anything has meaning, it is already connected 
iZeitschrift f. Psychologic, Erganzungsbd. V, pp. 215 ff. 



400 FUNDAMENTALS OF PSYCHOLOGY 

with something that is a part of the fundamental intel- 
lectual equipment of the individual. In this, to have 
meaning and to be recognized or cognized are approxi- 
mately identical. Thus we found that recognition con- 
sisted in attaching to the object or idea that is to be recog- 
nized some mark in itself familiar. The permanency of 
recognition, then, becomes the permanency of the older 
acquirement. In learning material that has meaning, the 
same factor is even more prominent. When the meaning 
of anything is understood, it is by that very fact united to 
the already familiar, becomes an instance under a general 
law or a general class, and that gives it in large degree the 
permanence of the general law. The meaningful material, 
by virtue of the fact of having meaning, will then be sure 
to belong to a larger group and so become easier to learn, 
and will also be connected with something that is already 
known and which permits the new to be understood. These 
two characteristics alone would go far toward explaining 
the advantage for learning of sense material. 

The importance of meaning can be seen to still better 
advantage in the type of learning most frequently prac- 
tised in adult life, learning the substance without the 
words. In this there must be some connection with a 
wider knowledge, or nothing can be retained. Almost any- 
thing that is understood can be retained for a little time, 
and to understand is, in essence, to connect the new with 
the previously organized knowledge. The degree of reten- 
tion depends in part upon frequency of repetition of the 
ideas, but much more upon the number of different ways 
in which the new is linked with the old, and thus to the 
completeness with which it is understood. While the pro- 
cess of understanding is more important on the whole than 
the formation of discrete associations, both must be pres- 



GENERAL ASPECTS OF MEMORY 401 

ent in some degree. Meaning has a basis in association, as 
has been pointed out, and, on the other hand, frequent 
repetition, even of nonsense syllables, tends to give them 
some meaning, however sUght. For practical purposes they 
are usually opposed. In rote learning, only the associates 
between the elements are considered; in sense material, 
the connections with the more general knowledge are em- 
phasized. When one is learning by rote, the meaning of 
the material may be lost sight of; in sense learning, the 
words may be altogether neglected. Either can be trained 
at the expense of the other. Individual differences in the 
use of one or the other are matters of training, and it is 
possible to acquire the ability to use either at will. 

General Aspects of Memory 

Individual Differences in Memory. — Not merely is 
there a difference in the degree to which rote and sense 
memory may be used, but there are differences in the ca- 
pacity of learning in general and in the aptitude for learn- 
ing different kinds of material. One of the most discussed 
is the difference between quick and slow learners. Ebbing- 
haus asserts that there is a law of compensation in learn- 
ing in that, if one learns slowly, one also forgets slowly. 
The instances chosen prove only that there is a greater 
percentage of saving for the slower learners, but the num- 
ber of repetitions required for relearning is least with the 
quick learner, and not so very much greater for those who 
learned more slowly in the beginning. Later experiments 
indicate that the quick learner is more effective in every 
respect. At the best, then, the slow learner has an advan- 
tage only in the percentage of repetitions saved, not in the 
amount that may be recalled by associates or in the time 
required for relearning. In several of the cases given, a 



402 FUNDAMENTALS OF PSYCHOLOGY 

quick learner would learn and relearn twenty-four hours 
later in fewer repetitions than the slow learner required for 
the first learning. 

Dependence upon Age. — The dependence of memory 
upon age is fairly well established. Measured by either 
the memory span, or the quickness of learning, or the im- 
mediate retention, memory increases gradually to thirteen, 
then improves very rapidly, to sixteen, and then more 
slowly to a maximum at twenty-two to twenty-five, then 
apparently persists approximately unimpaired throughout 
life, or at least until the onset of senile decay. Meumann 
grants that children may retain material once learned 
rather better than adults, a fact which accounts for the 
large percentage of our memories derived from early child- 
hood; but both immediate memory and ease of learning 
are greatest after maturity has been attained. Another 
factor that may be regarded at any moment as an indi- 
vidual difference, although it may depend upon habit, is 
the tendency to remember meanings or to remember by 
rote. This accounts for part of the apparent advantage of 
children. They are accustomed to learn by rote, and for 
that reason do it relatively better than do adults, who are 
at once lost in the meaning, and find difficulty in forcing 
themselves to attend to the words. The power of rote 
learning can of course be cultivated, and adults who have 
cultivated rote learning have an advantage in this also. 

Dependence upon Types of Imagery. — Still another 
more truly individual characteristic is to be found in the 
dependence of memory upon sensorial type. An individ- 
ual of a visual type is probably more successful in remem- 
bering words, colors, landscapes, and similar material; an 
individual of the auditory type, in remembering musical 
memories of all sorts, and the order of material that is 



GENERAL ASPECTS OF MEMORY 403 

learned. Which type is absolutely the best 15 not known, 
since investigations have not extended to a sufficiently 
large number of individuals. Meumann asserts that the 
visual memory is best for the retention of the elements, 
but that the motor-auditory obtains a more accurate grasp 
of the whole. In the work of the arithmetical prodigies or 
lightning calculators, differences in memory tj^e play a 
considerable part in determining the character of their 
feats. Two that have been studied, Diamandi and Dr. 
Ruckle, were visual in type, and one, Inaudi, was auditory- 
motor. The motor type did not lend itself to the reversal 
of operations, but with simpler processes was much quicker 
than the \dsual. On the whole the motor memory was 
quicker as far as it went, but much less flexible than the 
visual memory. When space factors entered, the visual 
far outstripped the motor-auditory. These are but illus- 
trations of differences in capacity that depend upon the 
memory type. 

Economy of Memory. — If one be asked how to learn to 
the best advantage, or how to improve one's memory or 
capacity for remembering, the best answer is to apply the 
rules given under the dift'erent heads of this chapter. If 
material is to be learned by rote, it is essential that there 
should be a large number of repetitions. In any case the 
repetitions should be divided over as many days as possi- 
ble and should be made by the whole method, and not part 
by part or bit by bit. The units should be grouped into 
wholes as far as possible, since this grouping reduces the 
work that must be done in learning. Above all, however, 
wherever the material to be learned has any meaning, it is 
essential to understand it. Material understood is more 
than half learned. In the process of understanding, it is 
well to approach the material from as many different 



404 FUNDAMENTALS OF PSYCHOLOGY 

points of view as possible. The greater the number of 
points of attachment, the more thorough is the under- 
standing, and also the greater the number of connections 
by which to arouse the memory in recall. Where matter is 
to be learned by rote as well as in substance, it is well to 
make two or three repetitions to understand the material, 
and then to proceed to commit to memory by repetition. 
It is essential also to attempt to repeat unaided as soon as 
possible. Usually after four or five repetitions, a free recall 
should be begun and frequent tests made of the parts that 
are least well recalled. 

Memory Systems. — Numerous attempts have been 
made since classical times to develop methods of aiding 
memory. Latin orators made use of the device of pictur- 
ing their orations upon the walls of different rooms of a 
house, one part on each wall of a room, and larger units in 
the same room. As they proceeded, they would picture 
themselves as walking through the house and reading their 
various headings from the walls. A more modern form of 
mnemonics, but one that goes back several centuries, con- 
sists in forming series of links, based upon chance asso- 
ciates between any two things that are to be recalled to- 
gether. Thus one may remember that A is the Greek let- 
ter delta by the series: triangle, pyramid, Nile, Delta. Or 
it may be remembered that Denver is the capital of Colo- 
rado through the lingo, Colorado, dodo, bird, dense air, 
Denver. Similar connections are made by these systems 
between any two facts that are to be connected. Obvi- 
ously any scheme of this kind will, in the long run, prove 
more harmful than helpful, as it involves making four or 
five associates where only one is needed, and the others are 
Hkely to develop inhibitions as well as waste time. It is 
much better to trust to forming the associations directly, 



GENERAL ASPECTS OF MEMORY 405 

and better still, if connections are needed, to base them 
upon some fundamental general principle. The system of 
the sciences is from one point of view merely a vast mne- 
monic system, a means of bringing a large number of iso- 
lated facts into connection with each other in some logical 
way. To make use of that as a means of remembering is 
to follow a plan that has been developed by the best minds 
of all times, rather than some chance scheme that has been 
hit upon by a charlatan. 

Transfer of Training. — A question of practical as well 
as theoretical interest is whether exercises in learning may 
be said to train memory, whether training in learning one 
sort of material or under one set of conditions is trans- 
ferred to learning some other material or under another set 
of conditions. All experiments in learning under experi- 
mental conditions show important improvement with prac- 
tice. There is also some improvement when one practises 
on nonsense syllables and tests by the capacity to learn 
sense material or by any form of rote learning. It has 
sometimes been held that memory was something that 
could be trained in and of itself like a muscle. Practically 
all modern evidence favors the view that the improvement 
is really in the methods that are used in learning. One be- 
comes accustomed to attending under the peculiar condi- 
tions of the laboratory; one forms, consciously or uncon- 
sciously, good habits of study, learns to read with the 
intention of remembering, and these factors may be car- 
ried over to any other material with advantage. From 
what we know, this is the only sense in which memory can 
be improved in any general fundamental way, and this is 
sufhcient to account for the improvement actually demon- 
strated. Another form of improvement can be noticed in 
connection with sense material, a form that comes without 



4o6 FUNDAMENTALS OF PSYCHOLOGY 

effort and is a necessary part of all learning. This is the 
increase in ability to understand, which develops with in- 
creased knowledge. As knowledge accumulates and is well 
ordered, more points of reference develop and each of these 
serves as a peg upon which new facts may be hung. Just 
as Dr. Ruckle's new numbers could be referred to numbers 
known as the squares and cubes of small numbers, and 
could be remembered in terms of those, so a new fact that 
can be given a place in the system of knowledge, as an in- 
stance of a familiar principle, is readily remembered. This 
system of knowledge grows with learning, and as each ad- 
dition to it is preparation for new acquirement, all- learn- 
ing may be said in this sense to train the memory. 

REFERENCES 

Colvin: The Learning Process. 
Meumann: The Psychology of Learning. 

MiJLLER, G. E.: Gedachtnisstatigskeit. Zeitschrift f. Psychol- 
ogie, Erganzungsbde. V, VIII, IX. 



CHAPTER XIII 
REASONING 

Closely related to memory is reasoning. Two processes 
are ordinarily included under reasoning. The first is the 
construction in idea of plans and machines that may 
later be applied to actual practice and built of real material 
instead of in idea. The second is a process of understand- 
ing and explaining natural events and phenomena. 

Reasoning as Planning. — In the first case we have a 
desire or need which must be satisfied or suppHed and for 
which none of the objects which are immediately seen or 
can be remembered will suffice. This is the process which 
is typical of invention and discovery, of planning and de- 
signing. The thought constructions save the time and 
materials which might be wasted in hit or miss trial. When 
a house is to be built, it is first thought through in detail 
or drawn with the different spaces allotted as they should 
be and the different materials decided upon. Then when 
the actual construction begins many at least of the different 
problems are settled. The other unforeseen difficulties 
that appear in the adjustment of various details are also 
first settled in thought. 

Reasoning as Understanding. — The second type of 
reasoning is typical of the attempts to understand natural 
phenomena or other events. It aims not at changing the 
course of the world directly, but at seeing why it works as 
it does. Of course ultimately this understanding of the 

processes of the universe may enable us to change them 

407 



4o8 FUNDAMENTALS OF PSYCHOLOGY 

in order better to comply with our needs. The process of 
reasoning with the end of understanding is t3^ical of 
science. The immediate ends of science are to understand. 
The two processes of reasoning are much aUke in the in- 
centives which induce them and in the method which is 
used. Still it is well to recognize them as distinct. 

Reasoning always Arises from a Thwarting of Progress. 
— Both forms of reasoning are occasioned by the feehng 
of need of change in a present condition. In the more active 
type — that of planning — we feel that the present situa- 
tion leaves something to be desired, and by reasoning we 
attempt to find a means of supplying that lack. In the 
second type — that of understanding — we feel puzzled 
over some occurrence that does not seem to run in the 
regular course, and we seek an explanation. Both may be 
said to arise from a thwarted purpose. In the first the 
thwarting comes from an inability to attain a desired end; 
in the second there is a failure to see why the particular 
event runs as it does. As an illustration of the first we may 
take the need of making a balky automobile go; of the second 
tj^e, an inabihty to understand why the sun rises in 
the north in the summer while we have always been told 
that it rises in the east. In both cases problems may present 
themselves as vague complexes, as mere feeling that some- 
thing is lacking and must be supplied. The initial active 
step in either case is to become definitely aware of exactly 
what is wrong. This is known as the process of judging. It 
consists, in either form of reasoning, in referring the felt 
need or the observed fact to a definite name and group of 
phenomena. To understand why the car stops it is neces- 
sary to examine part by part in the Hght of a knowledge of 
the machine or of experiences with other machines which 
have stopped in the past. The particular difficulty may be 



REASONING 409 

discovered upon examination to be due to a broken wire 
in the ignition system. This constitutes a reference of the 
vague general fact that the automobile has stopped to a 
defined class of reasons why it should stop. Similarly, the 
fact that the sun rises out of place or that it shines into a 
north window early in the morning leads to an appreciation 
of the general fact that it does rise far north in the summer 
and that this needs explanation. 

The Active Steps in Reasoning. — In each case, after 
the phenomenon has been discovered or expHcitly indi- 
cated, the active process of reasoning begins. The first 
step, when reasoning is viewed as planning, is to find some 
way of remedying the situation. This is always the longest 
and in many ways the most important operation. It con- 
sists in casting about until some idea occurs that will 
promise to supply the defect. After an idea has presented 
itself as to how the result may be achieved it is still neces- 
sary to convince one's self and often to convince others 
that the suggestion is correct, and that if put into applica- 
tion it would produce the change desired. This is the 
process of proof, and is the process that has always at- 
tracted most attention. It is the process that the logician 
identified with reason, although it is the one that is least 
active, and in many ways the least important. Reasoning, 
as we have said, always arises from a thwarted purpose, 
or felt need. The first stage, after this need is felt, is to 
analyze this need, to discover clearly what is wrong; this 
is judgment. Then one must find a solution; this is infer- 
ence. Finally it is necessary to show that it is actually 
a solution; this is proof. 

These various processes involve many of the association 
and other mental processes which have already been con- 
sidered. In addition there are three fundamental facts 



4IO FUNDAMENTALS OF PSYCHOLOGY 

or phases that have not been fully considered which are 
involved at each stage of reasoning, which we must dis- 
cuss here in detail. These are meaning, the concept, and 
belief. Meaning is important, since almost all thinking is 
in symbols, in language, or in ideas, that mean something 
different from what they are in themselves. The concept 
is closely related to meaning, since most of the processes 
that carry the meanings are concepts. Belief is important 
as a preliminary or substitute for proof in the acceptance 
of a solution, once it has been reached or has been sug- 
gested. These terms we may define and discuss as a pre- 
liminary to solving the problems themselves. 

Meaning 

Meaning and the Concept. — Meaning and the concept 
are in large measure correlative terms, as neither would have 
any significance in psychology were it not for the other. 
In its earliest form, meaning is the fact that one bit of men- 
tal content represents or stands for something else. A 
word stands for an object in our thought and may be used 
in its place in all of our thinking about that object. Mean- 
ing tends to become something almost as definite as the 
object itself. At least it becomes a mental characteristic 
of the object and a felt addition to the mental state, which 
is almost as important as, at times even more important 
than, the mental state itself. A picture or image of a more 
concrete type may also take on meaning, and come to 
represent a number of other images or objects as well as 
itself. In fact every mental state may be said to have 
meaning, in that it stands for something in addition to 
itself, and is important to us for what it means rather than 
for itself. This is the same condition which we found in 
perception, in that a sensation of one kind represents some- 



MEANING 411 

thing else and that something else really replaces it in our 
thought. We saw that a strain sensation represents a 
certain distance, and that when there is a certain strain 
in the eye-muscles we think of that distance although we do 
not become aware of the strain itself. A figure drawn with 
obtuse and acute angles represents a square figure in another 
plane of space; and we see that square figure, although 
we do not notice the angles that induce us to make the 
inference. All these may be regarded as instances of mean- 
ing or representation in perception. In each case a sensa- 
tion or group of sensations represents or stands for some- 
thing else; and in each case we become aware of what the 
sensations represent, not of the sensations that are actually 
given. 

The Nature of Meaning. — How one idea can thus 
stand for another needs to be examined more closely. 
A study of the conditions under which meaning originates 
indicates that it is at first a mere process of association or 
connection through contiguity. One idea tends to suggest 
the other because it has been seen at the same time with 
it. A man's name serves at first to recall the picture of the 
man ; then it is used in place of the picture, because we are 
certain that the mental picture may be aroused at any time 
that we desire to recall it, and we are satisfied with that 
feeling. Soon it also becomes associated with the capacities 
and activities of that man, and may serve quite as fully 
to represent him in thought as would the image itself. 
In fact, it often seems to be a more satisfactory representa- 
tive of his capacities and other more active and vital 
aspects of him than is the mental picture of him. It has 
been more often and more closely associated with him than 
has the picture, and so when we think of those aspects we 
may be more likely to recall the name than the image. 



412 FUNDAMENTALS OF PSYCHOLOGY 

This may be true especially of men whom we know through 
their writings or from reputation, rather than through their 
actual presence. In such cases, when the man is seen for the 
first time one may find one's self harking back in thought 
to the name, to find one's self saying in surprise, this is 
Ribot. The name in such cases gives meaning to the image. 
These associates cluster about the word and seem in 
many cases to give an entirely different feeling to the word 
from that which it would have without them. Probably 
a large part of any experience depends upon these asso- 
ciates. As in recognition, it seems that the associates are 
frequently aroused in slight degree when they are not suf- 
ficiently active to give a direct awareness of their presence. 
Thus a word with one group of associates will seem to be 
different from the same word with another group, although 
the associates themselves may not be definitely in mind. 
The meaning changes as the partially aroused associates 
vary. These vary under the influence of the mental con- 
text or attitude, as was seen in Chapter VI. This makes 
possible the use of the same word or sound for entirely 
different objects and ideas. Such a word as bar has a num- 
ber of altogether different meanings, and they seldom 
interfere with each other. If one thinks of an attorney, 
it has an entirely different meaning from that which it has 
as one thinks of a harbor, or of carpentry, or of a beverage. 
In each of these cases we may think of the word as a centre 
of associates which spring up as it enters consciousness. 
One group will come when the mind is in one attitude, 
and another is aroused when the mind is in a different atti- 
tude. Even when the associates are not definitely in mind, 
the meaning will be different under different conditions; 
this meaning, we may assume, is due to the different par- 
tially aroused associates. 



MEANING 413 

Meaning as Conscious Process. — In order to see clearly 
that there is a definite conscious process of meaning, we 
may artificially eliminate the meaning. This can be done, 
according to Professor James, by staring for a few mo- 
ments at a word in isolation. As one continues to hold 
the word in mind, it seems to become a mere group of letters, 
without any of the meaning that it has as one looks at it 
casually, or even any of the meaning that was present when 
the staring began. The ' feeling ' of the word is altogether 
different. One may believe that the associations, that were 
aroused at first, cease to be active during the long-drawn- 
out staring, and so meaning with its characteristic quality 
disappears. In general it seems that much of the con- 
sciousness that is aroused by the ideas that we have is 
due to meaning. We seldom if ever entirely dissociate a 
sensation or memory from its meaning, and much that we 
ascribe to the bare element is really due to the associates 
that it arouses. When we do by artifice divorce a sensation 
or memory element from its meaning, we are surprised to 
discover what it is. This is probably another effect of the 
doctrine frequently emphasized throughout, that nothing 
comes to mind alone ; or, in nervous terms, that an element 
never acts in isolation. 

Meaning Present when Associates are not Noticed. — 
It should be added that, even if we accept the assumption 
made above — that meaning is due to the awakening of 
old association paths — nevertheless, meaning persists 
when we are no longer aware of the associates themselves. 
This was seen to be true of recognition as well; and recogni- 
tion, we showed, was due to a similar complete or partial 
arousilig of associations. The matter may go even farther, 
in that meaning may be present when we are not even 
aware of the sensation or image that gives rise to the 



414 FUNDAMENTALS OF PSYCHOLOGY 

meaning. One is occasionally aware of meaning something, 
as when one intends to discuss a topic, although no words 
or other images are present, or are at least not distinct. 
This has led Kiilpe and others of his school and Wood- 
worth to assert that meaning may be a new form of con- 
sciousness, independent of all imagery. That one may 
think in meanings alone is what they call ' imageless 
thought.' Whether these cases are more than the final 
stage in the dropping out of associates, which are at first 
present, has been questioned. Certain it is that we find 
many cases in perception in which the sensation is not 
noticed in itself but only for the meaning that it carries. 
Strain sensations about the eyes are not noticed, but 
nevertheless they mean distance, and through this mean- 
ing we perceive distance. Similarly one is not aware of 
the sensations in reading, but only of the words seen or of 
their meaning. In recognition, we noticed that one might 
have a vague feeling of famiharity when the object that 
induced the feehng was not definitely in consciousness. 
All these instances are similar to the case of meaning where 
there is no image to bear or suggest it. It should in fairness 
be added that the holders of the theory that meaning is a 
new and peculiar form of consciousness are not convinced by 
this criticism. They insist that these are all cases in which 
the new element is the determining factor in consciousness, 
and think it needs no explanation. 

Concepts 

The Concept. — The fact that all ideas have an impor- 
tance only from their connections, and that all are really 
representative of something else, leads naturally to an 
explanation of the concept. Historically, the concept is 
the element or an element which is important only as it 



CONCEPTS 415 

represents something else. In general, it is defined as a 
mental process that represents general or abstract ideas 
rather than particulars. In the beginning we may regard 
the concept as representative of several different objects 
rather than of one alone. In this sense all common nouns 
are concepts. They represent all objects of a class in- 
differently. This notion of the concept offers no difficulty 
if we remember that all ideas are similarly representative. 
They all have meanings that reach beyond themselves. 
Each word or object has many associates, similar in some 
degree, which have been added from time to time. The one 
word representing the object is capable of recalling all of 
the group of associates, and stands for the members of the 
group because of the partial arousal of the associates, even 
when the whole group is not definitely or completely 
aroused. One has the feehng that one might recall them 
even when they are not actually recalled, and this feehng 
or a partial arousal gives the experience that we call the 
meaning of the word. 

Concepts Represent Abstract Qualities. — Concepts 
represent qualities as well as objects. In many cases the 
qualities which are represented may be regarded as th* 
characteristics of the objects that render them sufficiently 
alike to be grouped in a single class. In the recognition of 
animals as a class, it is the mass of quaHties that we call 
life that makes possible the grouping. We may become 
aware of these characteristics individually and give a 
name to each. This form of the concept — referring to 
a quahty — is quite as frequent as the concept which 
merely represents a class, and in many ways it is more 
important. After the members of a class have become 
connected through the possession of some one important 
quality or aspect, that aspect is selected, given an inde- 



4i6 FUNDAMENTALS OF PSYCHOLOGY 

pendent name, and comes to stand in thought as a real 
entity. In many cases the scientist establishes the in- 
dependent existence of what at first was merely a mark or 
characteristic of a class. Such are the physical concepts 
of heat, force, electricity, and magnetism, to mention 
only a few. How far these would be said to have real 
independent existence, and how far they are characteristics 
of a group, is a question which not all would answer alike. 
Certainly they are not merely class concepts; and, equally 
clearly, without them a large part of modern thinking and 
investigation would be much less effective than it is. 

Concept as Type. — Closely related to this form of the 
concept, which represents something abstracted from the 
particular ideas or experiences, is the sense in which the 
term concept is used as the quahty that is represented by 
the general idea rather than as the mental state that 
represents it. Thus, force, for example, is something which 
is never actually experienced in the form in which we think 
of it. It is an abstraction which we must use if we are to 
appreciate the physical universe clearly, and which is 
warranted by the fact that it is a necessity for clear think- 
ing. In this sense all knowledge is made up of concepts. 
The particulars are the raw materials from which the fully 
unified system is built. One may picture the system of 
knowledge as made up of various elements that have been 
fitted together to constitute a consistent whole. These 
elements are for the most part not given immediately in 
sensation, but are the results of various refinements, of 
various ways of working over the raw materials, until 
some order is brought into the originally inchoate mass. 
We have seen the process at work even in perception. 
As was pointed out there on several occasions, what is 
perceived is not merely a mass of sensations, nor is it a 



CONCEPTS 417 

single sensation that suggests some other single sensation 
or group of sensations; it is a type, an organized product 
of many experiences which have finally given rise to a 
construct consistent with all of our different related ex- 
periences. This it is that is in mind when a single stimulus 
presents itself. Thus, to repeat our simple instance, we 
see the top of a table as square, not because it is square 
on the retina, nor because we have seen it more frequently 
under conditions that make it appear square than when 
distorted by perspective, ■ — probably it never has been 
seen undistorted, — but because all that we know about 
the table top harmonizes with the assumption that it is 
square. When tested or measured it proves to be square; 
a similar surface must be made with right angles, it fits 
into square corners. It is beheved to be square because 
that assumption fits in with all of our other experiences. 

Development of Concepts. — It is by this method that 
most of the notions of external objects develop. Position 
is a notion that cannot be referred to any single experience. 
Depth also cannot be said to be merely the sensation of the 
motion necessary to reach the object, but is rather a con- 
cept or type developed through many tests, and accepted 
because it harmonizes or orders many different experiences. 
Space in general is a similar type. If we turn from per- 
ception to less objective things, the same principle may be 
applied. The development of the number concept can be 
followed among the different primitive nations. In northern 
Borneo, the natives still have no developed notion of 
number apart from objects. When counting they use the 
fingers and toes ; and when the number rises above twenty, 
another man is called and the objects are checked against 
his fingers and toes. The remnants of this counting can 
easily be traced in the decimal system and in the score. 



41 8 FUNDAMENTALS OF PSYCHOLOGY 

In this instance the concept carries with it more of the 
original sensory material from which it develops than do 
space and position, but in the course of time the separation 
from the concrete is complete; and, for us, number carries 
with it practically no implication of fingers and toes except 
for the use of a few words, such as digits. 

Concepts Alone in the Chinese Written Language. — Very 
important as evidence both of the way the concept devel- 
ops and also of the relative independence of the concept 
when developed is the written Chinese language. Instead 
of representing sounds as do the characters in the occiden- 
tal languages, the Chinese characters represent ideas. In 
consequence, two peoples like the Chinese and the Japa- 
nese, with altogether different spoken tongues, may use the 
same written language. The symbols in Chinese were 
originally representative of objects; but, with time, con-- 
venience in writing has changed them so that in many 
cases there is Kttle similarity between the object and its 
symbol. Very instructive evidence of the nature of ab- 
straction is the way more general ideas are represented. 
Thus morning is represented by the sun near the horizon; 
evening by the bird on its nest. Good is represented by 
the symbol of a woman and a child together. Less gallant 
is the symbol for treachery, which is three women together; 
and for strife or dissension*, which is two women under one 
roof. In general it will be seen that a-n object which is a 
frequent accompaniment of a general idea comes to repre- 
sent that idea. Interesting, too, it is to note that the orig- 
inal meaning of the symbols are usually not thought of, 
when used for these secondary representations of abstract 
ideas. 

Knowledge a System of Concepts. — Leaving out of 
consideration for the moment the question of how the con^ 



CONCEPTS 419 

cepts develop, it is evident that organized knowledge con- 
sists in its entirety of a system of concepts. When any- 
thing can be referred to a concept, we place it, we can use 
it, we understand. On the other hand, when it is possible 
to develop a notion or concept that will organize a group 
of facts, we accept the concept as true, and use it until 
some new facts appear that are out of harmony with it, 
when that concept is given up and another substituted for 
it. Just as in the perception of space, the concept or type 
is assumed to be real and all else is adjusted to it, so in 
science or philosophy or in everyday Hfe the concepts are 
accepted as the reals, other experiences are merely ap- 
pearance. The systems of concepts are by no means con- 
sistent with each other, but must be consistent within 
themselves. Thus, if one consider the experience of per- 
ceiving the table from the standpoint of the concepts of 
the different sciences, we would be told, on the one hand, 
that it was nothing but a mass of atoms of hydrogen and 
carbon and oxygen in different arrangements with a few 
odd elements thrown in; that its peculiar character de- 
pended upon the way the atoms were groupe'd in the mole- 
cules. For the chemist it is this and nothing more. For 
the physicist the picture changes. Atoms withdraw to the 
background, and forces come to the front. Gravitational 
attraction keeps it in place on the earth, and gives it weight. 
We see the table as a result of the vibrations in the ether 
which it reflects; and its color is determined by the rays 
that it absorbs and reflects. If one happens to be talking 
to a physicist of the latest school, electric waves are sub- 
stituted for the vibrations of the ether. In any case, ex- 
planation is in terms of a system of concepts, however the 
concepts may differ. The physiologist finds his explana- 
tion of the experience in the nervous structure of the eye, 



420 FUNDAMENTALS OF PSYCHOLOGY 

in photo-chemical processes in the rods and cones, in the 
excitations and responses of the neurones. The psycholo- 
gist finds the explanation in a group of sensations of strain, 
of light and shade, of images. These are the types or con- 
cepts to which experience is referred, as the psychologist 
attempts to understand it. In short, our simple experience 
has been dissolved in a great many different ways, no one 
of which leaves anything of the original experience; and 
yet without this dissolution into concepts, it could not be 
understood. 

No Understanding Without Concepts. — Without con- 
cepts all would be confusion. This is clear from a study of 
the early languages and the lower forms of human thought. 
It is asserted that among the lower South African tribes 
there is no notion of direction in the absolute sense. The 
individual gropes his way from place to place by memory 
of each landmark along the way, and has no idea in which 
direction he is going. He cannot keep his bearing even 
with reference to the rising or the setting sun. How con- 
fused his notion of the world must be, can easily be appre- 
ciated. Similarly, where numbers are restricted to a score, 
where length can be measured only in paces, or in days' 
journeys, and other concepts are equally faulty or alto- 
gether lacking, all thought must be decidedly vague and 
uncertain. Even the use of purely personal concepts of 
force, as in the explanation of the winds and other natural 
phenomena by spirits, and the generally accepted anthro- 
pomorphic explanation of events and causes, means that 
little progress can be made toward accurate understanding 
or use of natural forces. Adequacy of concepts means ade- 
quacy of understanding, and that in turn means successful 
action and application of means to ends. What experience 
would be like without concepts one cannot appreciate. It 



CONCEPTS 421 

would be of course a hopeless confusion, like waking from 
a bad dream into an entirely new environment. Nothing 
would be clear, nothing would be definite. To all intents 
and purposes, without concepts there would be no con- 
sciousness. Adequate concepts are the handmaidens of 
adequate thought. 

Concepts Develop by Trial and Error. — The problem 
of the origin of concepts as the elements of understanding 
has been one of the persistent problems of philosophy. We 
find that the general theories divide themselves, like the 
theories of space, into those which assume concepts and 
regard them as determining the course of development of 
knowledge, and those which would develop the concepts 
themselves from and through experience. Plato, for ex; 
ample, has in his ideas a system of concepts that are in- 
nate, the representatives in man of the eternal verities, 
through which all experience obtains what truth it may 
have. On the other hand, we have more empirical the- 
ories that would derive concepts from the experience of 
the individual. They regard the more abstract concepts as 
developed on the basis of individual suggestions worked 
over and modified to harmonize the experience of the race. 
This is essentially the suggestion that was made with ref- 
erence to the types in perception. They may be in part or 
at times derived by the accumulation of particular experi- 
ences that have been consolidated or modified by use. 
Very largely and in many cases, however, they seem to re- 
sult from hitting by chance upon some construction that 
harmonizes with the experiences. When a construction is 
found that meets this test, it is accepted. Certain it is 
that concepts are modified with the passage of time and 
the growth of knowledge, and it is just as certain that a 
concept is seldom the direct product of the action of the 



422 FUNDAMENTALS OF PSYCHOLOGY 

senses. In the formation of laws, experimental science 
shows a tendency to consolidate particular observations 
into generaHzations. In this consoKdation, trial and error 
are important factors. However derived, we insist that 
our knowledge, as used in thought and developed through 
perception, becomes largely a system of concepts, of types, 
and that these serve to explain the concrete, and in many 
cases in themselves to constitute the concrete. Without 
concepts knowledge would be no knowledge but a mere 
mass of confusion. 

Concept as Representative Idea and as Type. — Two 
forms of the concept may accordingly be distinguished. 
The first is a definite mental state that means a number 
of particulars or a number of general qualities of any sort. 
This takes the form of a word, a typical group of sensa- 
tions; or it may be reduced to nothing or very nearly 
nothing but the meaning, the reference itself. The second 
form is an organized idea, a type that has been proved by 
tests to satisfy many experiences, and in consequence is 
accepted as real. It is this concept that is usually meant. 
It is what we accept as the external object, of common 
sense, it is the fundamental structure or force or principle 
of explanation in natural science, or in psychology. In 
many cases these types, too, are not absolutely clearly pic- 
tured but are represented in consciousness in some sche- 
matic fashion. At other times, as in perception, the types 
constitute the clearest and most definite structures of con- 
sciousness. They are consciousness, and all else is subor- 
dinated to them. In every case they are all that we are 
really conscious of at the moment, whether they be merely 
meant, or actually reproduced in all their clearness. 

The Stages of Active Reasoning. — At every stage in 
active reasoning, use is made both of meaning and of the 



CONCEPTS 423 

concept. Reasoning has as its object either bringing order 
into experience or discovering ways of improving the en- 
vironment, and justifying suggestions for new advances. 
In both cases, reference to the estabHshed system of knowl- 
edge, to concepts and generally accepted laws, plays a 
prominent part. Practically all reasoning operations deal 
with real things or their symbols. Each of the four 
processes into which reasoning was divided makes use of 
concepts. 

The reasoning process is initiated by the lack of a 
satisfactory concept or the need for the solution of 
some difficulty. 

In the solution of a problem or in obviating a diffi- 
culty, the judgment- consists merely in referring the 
difficulty to a concept. One is prepared to start on' 
the solution when one appreciates what the difficulty 
is, which involves assigning it to a known class or a 
clear idea. 

The inference, or problem of finding a solution, in- 
volves concepts only in that it is customary to try one 
after another of the familiar concepts to see if they fit. 
Where an old concept is used, it is used in a new 
connection if the reasoning is real, and the solution 
original. 

In the final stage, proof, a concept or old organized 
experience is the factor that induces belief. It is only 
as one can refer the suggested solution to some system 
of organized knowledge, to a concept or system of 
concepts, that conviction of the truth will be induced. 
As we shall see in detail in each stage, reasoning in 
all of its parts is possible only through the use of a 
developed series of concepts. 



424 FUNDAMENTALS OF PSYCHOLOGY 

The Initiation or the Reasoning Process 

The Initiation of the Reasoning Process. — Reasoning 
as a whole must have a positive stimulus. The problem is 
always forced upon the individual by some inadequacy 
of old habits or of old thoughts, by something that goes 
wrong in the ordinary routine. Where habit and routine 
suffice, one never reasons. Necessity is the mother of all 
thought, as of all invention. Reasoning results when a 
man is thwarted in his mental or physical progress. On 
the mental side some fact presents itself that will not fit 
into the theories already developed. The number of spe- 
cies of beetles challenged Darwin to discover a reason, the 
ffight of birds and insects challenged Langley and Wright 
to find some mechanical means of imitating them. Each 
suggestion that ideas may be realized starts the discoverer 
on a quest for the means. Granted the problem, the next 
stage is an analysis of the problem into its elements or 
conditions to obtain a better understanding of what is to 
be done. 

Judgment 

Judgment, the First Active Step in Reasoning. — The 

first step either in understanding a situation or in finding 
a way out of a difficulty is an analysis of the situation. 
This process of analysis consists of a reference of each part 
of the problem to its peculiar concept or class. The pro- 
cess of reference to a type is known as the judgment. In 
the solution of any mechanical problem, the building of a 
bridge, for example, it is necessary to reduce the various 
strains to their components, to measure the intensity of 
each, before means can be found for resisting them. In 
designing a building, the engineer goes beyond the ordi- 



JUDGMENT 425 

nary rule of thumb, determines how much pressure the 
building will exert downward, how much will be expended 
in lateral thrusts, what the wind pressure is likely to be at 
a maximum, and only when these various components of 
the problem have been determined is he ready to decide 
what material must be used and how the structural ele- 
ments may be distributed. Each of these steps is an analy- 
sis of the problem into simpler, known elements. The 
process of analysis is essential at every step in advance of 
action. It consists in referring the new to old and famihar 
experiences so far as the new offers points of similarity 
with the old. This is the first place at which the back- 
ground of older experience aids in the new construction, in 
progress of any sort. Only in so far as the problem can be 
reduced to its parts and the parts referred to estabhshed 
concepts can it be said to be understood, and only then 
is it possible to go ahead safely. To act before the 
situation is understood is to act in the dark and in- 
effectively. 

The process of judging consists of the reference of a new 
experience or an entering sensation to an old concept. 
From one point of view it is simply the perception process 
over again. A stimulus presents itself, and, before it is 
really conscious, it is referred to some old type; it is given 
a meaning, and thereby becomes fully conscious. The 
process called judgment by the formal logician is approxi- 
mately the same, although more expHcit and definitely rep- 
resented in words. Thus 'man is mortal' is a judgment; 
man is the subject, mortal is the predicate. The subject 
represents the presented, the thing given to be understood, 
and the predicate the concept by which it is explained. 
The process of judging brings the new under some head or 
category already established. 



426 FUNDAMENTALS OF PSYCHOLOGY 

Judgments of Relation and Evaluation. — In addition 
to this use of the term 'judgment' to designate the reference 
of the unknown to some definite concept, psychologists 
use it also to indicate comparison and evaluation, uses 
more closely related to that of everyday speech. One is 
said to judge when one compares two lines; and also when 
one estimates the value of anything, assigns the money 
value to a horse or other article of merchandise, or esti- 
mates the guilt of the prisoner at the bar. In each case 
there is approximately the same process. In evaluation of 
any kind, one has a scale of values that has been devel- 
oped in the course of many experiences. An article is 
given its place in the Hst on the basis of various similarities 
to things judged before, some expHcit, some implicit and 
indefinite. A similar process is present in judicial deci- 
sions. A particular crime is referred to the general scale of 
crimes and the punishment is affixed in accordance with 
the scale. Comparisons are also references to concepts, 
but the concepts are typical relations, not typical things. 
Relations are as truly concepts as are space or time. The 
relations of greater and less are typical relations, developed 
to make it possible to understand certain phases of experi- 
ence. To measure, it was necessary to develop the con- 
cepts of relation in space and time and mass; and measure- 
ment is the foundation of civihzed hfe. When an observer 
asserts that a Hne is longer than another, he merely looks 
from one to the other in immediate succession, and the 
concept greater or less suggests itself; the pair is referred 
to one class or the other immediately. The process is just 
as unitary as is the recognition of a new object or any 
similar classification. The judgment in general is a refer- 
ence of a new thing or situation to a famihar head, the ref- 
erence of a particular or unknown to a general t3^e, a 



INFERENCE 427 

reference that prepares one to treat it adequately. In our 
specific practical case, it is a process of analyzing the ele- 
ments of the problem in preparation for its solution. 

Inference 

The Process of Finding a Solution of the Diffi- 
culty. — When the problem has been stated and under- 
stood, the next step is to discover a solution. Finding 
the solution, inference in our sense, consists in a process 
or series of processes of association. If, when the judg- 
ment is attained, the new situation is reduced to famihar 
elements, the solution is practically completed. The older 
solutions may suffice or may be combined in the attain- 
ment of the new desired end. In these cases, association 
under the suitable more general forms of control may be 
all that is necessary. In many other instances the process 
cannot be reduced to laws, although probably each sugges- 
tion is controlled by definite laws of association. One can 
be sure only that there will be many attempts of different 
sorts before the solution is finally reached. Inference has 
more points of resemblance to the efforts of an animal 
struggling to get out of a box or of the man with a new 
puzzle than to the ordinary notion of the action of a cal- 
culating human being. In these cases the process is one of 
repeatedly trying, with a readiness to reject all but the 
right solution. 

Inference a Process of Trial and Error. — When a per- 
son tries to solve a puzzle, he makes one movement and 
than another, until finally by chance he is successful. In 
thinking out the solution for a problem very much the 
same process is used ezcept that the trials are only in 
thought. One thinks of one after another of the possible 
positions of earth and sun in trying to find a reason for the 



428 FUNDAMENTALS OF PSYCHOLOGY 

sun's appearance so far to the north (to continue the pre- 
vious example). If the first one will not work, another is 
tried. If that is rejected, a third is presented. The process 
continues until one is hit upon that seems satisfactory. In 
finding a solution of a difficult mechanical problem, the 
process of trying suggestions and rejecting them may last 
for hours, and of course in important inventions the trials 
may continue for years before the right solution is hit 
upon. Frequently, an approximation to the solution will 
be reached, and then the process of transforming or per- 
fecting will go on by the same method for an equally long 
time before what can be considered a complete solution 
will be hit upon. In the case of actual inventions or the 
solution of actual problems, the final satisfaction may come 
almost by accident, if we can distinguish between accident 
and intention in such an operation. The list of great in- 
ventions that have been made by accident is very long. 
Almost the only rule that can be given for the attainment 
of the desired end is to keep trying. Persistence is the 
only virtue; the rest is very largely a matter of chance. 
There are certain minds in which ideas spring readily, that 
seem fertile in suggestions of all sorts; certain others that 
practically never get away from the commonplace, from 
the prosaic memories. Blessed is he whose psychophysical 
disposition is of the former type. The man who happens 
not to possess this touch of genius can do nothing but 
substitute persistence and methodical trial for the quick 
advances of the chosen few. No rules can be given for 
making the unfertile brain fertile, nor for the better use of 
the fertile brain. 

In the unusualness of the associations and connections 
that are made lies the one point of similarity between the 
abnormal or insane brain and the brain of genius. Both 



INFERENCE 429 

are constantly calling up ideas in connections that would 
be impossible to the average mind. Tests of the associa- 
tions of the insane show that their range of associations for 
a given set of words is very much greater than for the 
normal man. The results obtained by the man of genius 
prove the same departures from the commonplace, — in 
this case called original. The difference between the two 
sorts of mental fecundity is found in the nature of the 
originality. In the insane there is little control, the asso- 
ciates are not at all restricted by the nature of the en- 
vironment, or by any appropriateness to the situation. In 
the effective man of genius, they are checked and re- 
strained to correspond to the wider demands of the mo- 
ment. The second still more important difference is to be 
found in the repression on the part of the norma] man of 
the suggestions that are not suited to the occasion. The 
speech of an insane man may be merely a 'word salad,' an 
outpouring of words in any connection; in the normal 
these absurdities are inhibited, and if they present them- 
selves at all, only those are uttered that pass the censor 
of common sense. Ability to distinguish between the ap- 
propriate and the inappropriate is the primary mark of 
the normal as opposed to the abnormal. This serves, too, 
to emphasize the stages of the inference. One must first 
have the suggestion that is to constitute the solution, but 
must also have the capacity of knowing when the right 
solution has made its appearance. In this, reasoning is 
one more process in which we must distinguish between 
obtaining the suggestion and passing upon it. Sufficient 
freedom in suggestion is desirable, but absolutely essential 
is the capacity to appreciate the right suggestion when it 
comes, and to be satisfied with no less than the full solu- 
tion. 



430 FUNDAMENTALS OF PSYCHOLOGY 

Sometimes the right suggestion comes by chance, some- 
times it appears when thinking of something else, some- 
times one is merely fumbHng with the object that one 
wants to improve in some way, and makes the proper 
change without any preliminary thought, sometimes it is 
said inventions have been dreamed. Jastrow quotes an 
instance of an archaeologist who dreamed the reconstruc- 
tion of the results of certain of his excavations and found 
that they were adequate. It is said that the eccentric on 
the steam engine was invented by the boy who had been 
set to open and close the valves when the piston should 
change its direction. When he saw some boys he wanted 
to play with, it chanced that lie saw a place to put a stick 
where it would do the work he was doing, so slipped it in 
and went off to play. Whether the anecdote be true o/ 
not it illustrates how inventions may be made. It makes 
no difference how the suggestion comes, provided it is rec- 
ognized as appropriate when it comes, for inference is thep 
complete. Obviously it is quite as important to make 
proper selection from among the suggestions, as it is to 
have the suggestion. In this respect reasoning is like 
memory. The associations that arise in the attempt to re- 
call, correspond to the suggestions in reasoning. Passing 
upon the correctness of the recall found in recognition cor- 
responds to acceptance of the solution. We have seen 
that this is also true of the typical actions. All learning 
is a process of hitting upon a movement by chance and 
retaining it if the results are satisfactory. 

Belief and Proof 

The Nature of Belief. — It is particularly essential, then, 
that we should understand this testing or censoring pro- 
cess in connection with reasoning. Two phases may be dis- 



BELIEF AND PROOF 431 

tinguished. One, belief, is implicit, comes immediately and 
offers no definite consciousness of the conditions that lie 
behind it; the other, proof, is more explicit, in that it at- 
tempts to make clear why the thinker believes, and why 
others should accept the inference. Belief gives no war- 
rant for itself; a man knows that he believes, but can tell 
why only from a study of the conditions under which be- 
lief makes its appearance. Neither the feeling of belief 
nor the conditions that compel belief are fully conscious. 
In fact, the feeling of behef can be described best in nega- 
tive terms. We believe all that is not doubted, — the per- 
sistent, unquestioned presence of any idea constitutes be- 
lief. Doubt, on the other hand, comes with alternations in 
the interpretations, is due to a constant change from one 
to another of the ways of looking at an object. The cause 
of the fluctuation is to be found in the changing points of 
view from which the fact is considered, — in the different 
complexes of experience that serve to bring up first one in- 
terpretation, then another. Thus, if one is considering a 
general problem, for instance a favorite of the economists 
— the advantages of controlled monopoly as opposed to 
unlimited competition, — one will think of the importance 
of large production, of the encouragement to capital from 
certain returns, on the one side, and will believe in monop- 
oly; when one thinks of the tendency of human nature to 
think first of its own advantages, and of the growing cal- 
lousness of the dictator to those dependent upon him, per- 
mission to combine seems undesirable, and behef in mo- 
nopoly is refused. The checks that come from state control 
will remove the doubt for a moment until the difficulties in 
exercising impartial control present themselves, when the 
old doubt reasserts itself. Doubt is an expression of the 
conflict in various beliefs, and the beliefs in turn depend 



432 FUNDAMENTALS OF PSYCHOLOGY 

upon the presence of various groups of experiences which 
make for the prominence of one attitude or another to- 
ward the assertion that is questioned. 

In its less exphcit forms belief seems to be an expres- 
sion of the harmony of a particular statement with the 
dominant group of experiences. This may be seen to ad- 
vantage in the changes in belief as different possibilities 
are considered. When one is caught off one's guard, when 
a proposition is viewed in the Hght of a limited group of 
experiences, one will believe things which would not be 
believed under ordinary circumstances. An exaggeration 
of the condition is seen in the dream, where we may as- 
sume that large areas of the cortex are inactive, and only 
the few active cells control consciousness. Then one will 
believe many constructions that are rejected as soon as one 
wakes. The dream need harmonize only with the partial 
consciousness, but as soon as one wakes it is necessary that 
it harmonize with all portions. This it fails to do, and it is 
then at once seen to be bizarre. In the play attitude, or in 
the artistic attitude as in novel reading, one may volun- 
tarily hold part of consciousness out of action and pass 
upon the game or the work of art in the light of a partial 
experience. In this mood the result is accepted as true for 
the moment, although one is aware that it will not seem 
true as absolute fact. In general, belief is agreement be- 
tween the construction of the moment and the total ex- 
perience. The awareness of the agreement no more implies 
the presence in mind of all of the facts that are involved in 
passing upon the experience than recognition implies the 
presence of the associates that give the entering impres- 
sion a place in the past, or the meaning of an image in- 
volves the full presence of all that is meant. Rather the 
thing believed merely holds the centre of the stage without 



BELIEF AND PROOF 433 

wavering or opposition, and that, with possibly some slight 
feeling, constitutes belief. 

Proof a Justification of Belief. — While belief is sufh- 
cient justification for a conclusion on the part of the per- 
son who believes, the conclusion may not appeal so strongly 
to the listener or to others. It is this fact which makes 
proof necessary. Since justifying the conclusion is the one 
part of the reasoning process that is self-conscious, it is the 
process to which the formal logician has devoted most at- 
tention and which he is inclined to consider the only part 
of the reasoning process. Two forms of proof are to be 
distinguished, the deductive and the inductive. The typical 
deductive proof is through the syllogism, and this consists, 
in essentials, of referring the particular conclusion to some 
generally accepted principle, to a general law that is typi- 
cal of all others. Just as the judgment consists in refer- 
ring some particular object or difficulty to a typical diffi- 
culty or concept, the proof consists in finding a universal 
statement under which the particular conclusion that has 
been obtained may be brought and thereby made to seem 
true. The mere mention of a suitable general law arouses 
the peculiar cortical irradiations of associations that excite 
belief. First it should be said that nothing is proved that 
is not questioned. For one's self, belief suffices, and for 
most of the statements of everyday life as they are made 
to others no proof is necessary. Proof is given only when 
one hears or fears objection from one's listeners, or when 
one desires to test the truth of the conclusion for one's self 
in an explicit form. 

Deductive Proof. — The oldest and most frequently used 
form of proof is the deductive. In essentials this consists 
in referring the new or questioned solution or invention to 
an old or familiar class. In simple cases the famiUar class 



434 FUNDAMENTALS OF PSYCHOLOGY 

is merely mentioned. In more complicated instances the 
given problem is analyzed into a number of simpler ele- 
ments and it is shown, as in a problem in physics, that the 
solution in question makes use of a number of the simpler 
and more familiar steps. The formal logician has reduced 
proof to a schematic form in the syllogism. The syllogism 
is a group of three statements, of which the first contains a 
famiUar general statement which is used to justify the 
conclusion. The statement to be proved is put last and 
the two are united by a statement which indicates the rela- 
tion. The general statement is known as the major premise, 
the connecting statement is the minor premise, and the 
statement to be proved is the conclusion. Thus to choose 
a favorite instance, one might desire to prove that Socrates 
would die some day by asserting the unquestioned general 
principle that all men are mortal. This takes the form 

All men are mortal, {Major Premise) 

Socrates is a man, {Minor Premise) 

Therefore Socrates is mortal. {Conclusion) 

The reader can give this argument a setting if he imagines 
the members of the Areopagus arguing over the feasibility 
or desirability of inflicting the death penalty upon Socrates. 
This syllogism might be used either to meet the statement 
that it was not possible to inflict the death penalty, be- 
cause of the prominence of Socrates; or it might be made 
by one who objected to the death penalty on the ground 
that Socrates would die anyway in the natural course of 
events and so would not be a permanent danger to the state. 
It is obvious that the incentive to the syflogism must 
come from some one who has asserted the conclusion, and 
has had it chaflenged. The syllogism is a form of proof, not 
as is frequently asserted a method of reaching conclusions. 



BELIEF AND PROOF 435 

The syllogism is effective for proof just because it con- 
nects the new with an already accepted fact or group of 
facts. When the reference has been made, the belief that 
attaches to the old and familiar is transferred to the new. 
The effect seems to be one of arousing masses of old ex- 
perience which by their very arousal serve to stimulate the 
beUef attitude. The statement can add nothing to the 
new and must already be known, or it would not be ac- 
cepted by the man who is convinced. The utterance of 
the general principle seems to arouse the memories of the 
older cases and to crystallize them. Belief follows. The 
essence of the syllogism consists in this reference of the 
doubted to a familiar group. It may be given less formal 
expression and be equally effective. James, for example, 
shows that if one were asked why one placed a bit of match 
under one side of the chimney of a smoking lamp, the 
device could be justified by saying that it would admit air. 
The value of this might be questioned also, to be justified 
by reference to the fact that burning is a form of oxidation 
and will not be complete when the supply of air is defi- 
cient. If that were questioned, one would be compelled to 
refer to chemical formulae. In fact complete proof on any 
point might require reference through a large number of 
steps. Each of these might be put in the form of the 
syllogism. Fortunately, a reference to one more general 
principle in any brief way usually is sufficient to arouse 
belief. 

Inductive Proof. — The other form of proof, the induc- 
tive, consists in counting instances, in determining how 
often the conclusion is true. If in the past a suggestion 
has worked on every occasion, we are prepared to accept 
it as true. The effectiveness of this proof Kes in the actual 
study of past cases or in experimental repetition and veri- 



436 FUNDAMENTALS OF PSYCHOLOGY 

fication of the conclusion. From a study of the vital statis- 
tics one knows inductively that all men die. One knows 
that an aeroplane will fly, because it has flown. The whole 
proof is dependent on assuming that what has happened 
will happen. In one sense the two proofs tend to come to- 
gether, since of the empirical proofs only those are accepted 
which are in every way similar, which can be referred to the 
same general principle. On the other hand, the general 
principles that constitute the major premises of syllogisms 
and the accepted truths are probably in the last analysis 
derived from experience, but experiences coordinated and 
tested by particular appHcations and by their harmony 
with other general principles. A general principle fre- 
quently starts as the result of a few observations, is tested 
by other observations, then is compared with other general 
principles that have also been suggested and tested by other 
single observations, and, if all harmonize, it gradually comes 
to be generally accepted. In most subjects controversies 
over general principles are current at all times, because 
each is in harmony with certain experiences and out of 
harmony with others. Settlement comes with more accu- 
rate analysis of the problem, with more careful study of 
the facts, and, where experiment is possible, by making 
crucial tests of each. But in no case is it possible to say that 
organized previous experience has not had some share 
in the proof, nor is it possible to assert that observation of 
particular experiences, induction, shall not have contributed 
something. When reference to generahzed earHer experi- 
ence is more in evidence, the proof is called deductive; 
when particular cases, statistics, or experiments play the 
larger part, the proof is known as inductive; but neither 
can be completely divorced from the other. 



GENERAL REMARKS ON REASONING 437 

General Remarks on Reasoning 

Summary. — That the stages of reasoning may be as we 
have stated them — (i) the presentation of the problem 
that comes by a thwarting of the progress of action or of 
thought, (2) the judgment or analysis of the problem into 
its elements and the reference of each to its appropriate 
class or concept, (3) the inference or discovery of the solu- 
tion by much casting about, and finally (4) proof, ■ — may 
be seen by a study of the way in which Darwin and Wallace 
developed their doctrine of natural selection. It happens 
that in this case two men, travelHng independently prac- 
tically the same course, arrived at the same conclusion, and 
we have the process recorded by one of them and confirmed 
by mutual friends. Dr. Wallace,^ in modestly disclaiming 
any priority to Darwin in the discovery, traces in a paper 
before the Linnaean Society the facts that led both to 
hit upon the idea and to its statement. First with reference 
to the formulation of the problem: 

"First (and foremost as I beheve) both Darwin and myself 
became ardent beetle-hunters. Now there is certainly no 
group of organisms that so impresses the collector by the 
almost infinite number of its specific forms, the endless 
modifications of structure, shape, color, and surface-mark- 
ings that distinguish them from each other, and their in- 
numerable adaptations to diverse environments. . . . 
Again, both Darwin and myself had, what he terms ' the 
mere passion of collecting.' ... I should describe it 
rather as an intense interest in the mere variety of living 
things — the variety that catches the eye of the observer 
even among those which are very much alike but which are 
soon found to differ in several distinct characters. Now it 

1 The Origin of the Theory of Natural Selection, by A. R. Wallace, Pop. 
Sci. Monthly, Vol. LXXIV, pp. 398 ff. 



438 FUNDAMENTALS OF PSYCHOLOGY 

is this superficial and almost childlike interest in the 
outward form of Hving things which, though often de- 
spised as unscientific, happened to be the only one which 
would lead us towards a solution of the problem of species. 
... It is the constant search for and detection of these 
often unexpected differences between very similar creatures, 
that gives such an intellectual charm and fascination to the 
mere collection of these insects; and when, as in the case 
of Darwin and myself, the collectors were of a speculative 
turn of mind, they were constantly led to think upon the 
'why' and the *how' of all this wonderful variety in 
nature — this overwhelming, and, at first sight, purposeless 
wealth of specific forms among the very humblest forms of 
Hfe. . . . Then, a Httle later ... we became travellers, 
collectors, and observers in some of the richest and most 
interesting portions of the earth; and we thus had forced 
upon our attention all the strange phenomena of local and 
geographical distribution, with the numerous problems to 
which they give rise. Thenceforward our interest in the 
great mystery of how species came into existence was in- 
tensified, and — again to use Darwin's expression — 
'haunted' us. 

"Finally, both Darwin and myself, at the critical period 
when our minds were freshly stored with a considerable 
body of personal observation and reflection bearing upon 
the problem to be solved, had our attention directed to the 
system of positive checks as expounded by Malthus in his 
'Principles of Population.' The effect of this was analogous 
to that of friction upon a specially prepared match, pro- 
ducing that flash of insight which led us immediately to 
the simple but universal law of the 'survival of the fittest,' 
as the long-sought effective cause of the continuous modi- 
fication and adaptation of hving things." 



GENERAL REMARKS ON REASONING 439 

This shows that the problem had been set for both by 
almost the same conditions and that the solution had been 
attained in the same way, but the method of proof devoted 
to the suggestion was altogether different. Darwin spent 
thirty years in collecting and in writing out the evidence 
with only one mention of his theory to Sir Charles Lyell. 
Wallace, on the contrary, sat down at once, wrote a sketch 
of his theory, and, curiously enough, sent it to Darwin with 
the request that it be pubhshed. On the advice of friends 
Darwin presented the paper with a sketch of his own theory 
to a meeting of the Linnaean Society July i, 1858. Darwin 
said that even the words of Wallace's paper were so nearly 
like his own that one might have supposed that he must 
have seen it before he wrote. Wallace emphasizes the 
influence of similar circumstances upon the common result: 

" This view of the combination of certain mental faculties 
and external conditions that led Darwin and myself to an 
identical conception also serves to explain why none of our 
precursors or contemporaries hit upon what is really so 
very simple a solution of the great problem. . . . And 
now to recur to my own position, I may be allowed to make 
a final remark. I have long since come to see that no one 
deserves either praise or blame for the ideas that come to 
him. . . . Ideas and beHefs are certainly not voluntary 
acts. They come to us — we scarcely know how or whence, 
and once they have got possession of us we cannot reject 
or change them at will. It is for the common good that the 
promulgation of ideas should be free — uninfluenced by 
either praise or blame, reward or punishment." 

In this sketch Wallace marks out explicitly three of our 
stages — the arousal of the problem, the hitting upon the 
solution, and the proof. The second, the analysis of the 
problem or judgment, can be seen implicitly in the many 



440 FUNDAMENTALS OF PSYCHOLOGY 

forms that the problem took as the how and why of 
species became prominent at different times. Observation 
will show that any clearly formulated bit of reasoning 
takes essentially the same course. Most of the thinking 
of our daily life, even in important decisions, stops with 
the impHcit behef. The formal justification of the conclu- 
sion is not made. However, as we have seen, the unformu- 
lated but organized earlier experience is at work in accepting 
or rejecting these conclusions through the immediate belief 
processes, just as it is in the more formal operations. The 
warrant is the same, although the form in which it is ex- 
pressed is different. 

In reasoning, then, we see an advance made upon the 
accumulated knowledge, but an advance that is always 
made possible and controlled by that accumulated knowl- 
edge. One understands the new presentation and the new 
difficulties in terms of the organized old experiences, the 
t>pes and concepts; one obtains suggestions for new solu- 
tions on the basis of analogies with the old; and, when 
obtained, the suggestions for new solutions are justified 
and tested in advance of actual use in the Hght of the organ- 
ized knowledge. While new experiences and new trials are 
constantly increasing the sum total of knowledge, it is only 
by virtue of the previous accumulations and organizations 
that the new can be understood and that one may venture 
to test the new suggestions in action with even fair assurance 
of success. 

REFERENCES 

Titchener: Experimental Psychology of the Thought Processes. 

Dewey: How We Think. 

Dewey: Studies in Logical Theory. 

Pillsbury: The Psychology of Reasoning. 



CHAPTER XIV 
IMAGINATION AND DREAMS 

A LARGE part of our life sleeping and waking is spent in 
mental processes, intermediate between remembering and 
reasoning, which passes under such terms as imagination, 
revery, and day dreams. Even during sleep we have the 
conscious processes that we know as dreams. These various 
processes are alike in that they are due to largely uncon- 
trolled associations which continue without definite purpose 
and give pleasure because of the nature of the constructions. 
The laws of origin of the imaginative processes are approxi- 
mately the same as those for memory and reasoning, but 
the ends and controlling processes are very different. 
Reveries are evoked in accordance with the laws of associa- 
tion, as are memories and the products of reasoning; but 
the constructions are new, and consequently cannot be 
recognized, as the products of memory can. At the same 
time imagination differs from reasoning in that reveries 
have, at most, a very limited truth; they are not believed, 
or are believed to be true only under very special condi- 
tions. If we seek the criteria of the group we find it in a 
lack of definiteness rather than in any positive character- 
istics. It is marked by the free action of the mental 
machinery. 

Imagination and Life. — It is into this type of mental 
life that we fall the moment we are free from a serious task. 
It must be confessed that it occupies many of the intervals 
in serious tasks, in many cases time that should be given 

441 



442 FUNDAMENTALS OF PSYCHOLOGY 

to the duties of life. When the clerk at his desk has a 
moment he finds himself constructing for himself a world 
that is more pleasant than that in which he Hves. The stu- 
dent, during the uninteresting periods of a lecture, finds his 
mind wandering off to a world of future conquests, or to 
imagined changes in his lot. The ploughboy fills his time 
picturing a state in which he will sit in the house and direct 
the labor of others, and no longer hold the handles of 
the plough. The spare time of all alike, high or low in 
station, intelhgent as well as unintelKgent, is spent in spin- 
ning fancies. Thinking towards a definite goal is a matter 
of effort, of distinctly greater effort than the purposeless 
wandering of the mental images. 

The types of these imaginings range from passing day- 
dreams, unrecorded and transient, to the work of the novelist 
or the poet, and the creations of the painter, sculptor, and 
musician, on the one hand, and to the great constructive 
works of the inventor on the other, as the imaginative 
process merges with reason. If we were to give a complete 
explanation of these simpler states of mind we would at 
once have a theory of art, in all of its forms, and of certain 
of the achievements of the inventor. 

Play 

Imagination and Play. — - One can find an analogy for 
operations of imagination in the purposeless activities of 
animals and children, which we call play. Here on the 
active side we have the same series of tendencies, probably 
the same control or lack of control that we find in the men- 
tal state that we have been describing. The cause of play 
is, like the process of imagination, the inability to keep 
still, the activity of the neuromuscular mechanism, that 
must respond to every stimulus with movement. This 



PLAY 443 

overflow of activity, the inability to remain quiet, explains 
the constant movement of the child; it does not explain 
the particular form that the movements shall take. Many 
of the movements are determined as much by the operations 
of the laws of imagination as is the mental process itself. 

Play as Instinct. — Some plays are definitely instincts; 
but again, as in imagination, the instinct is evoked by a 
stimulus or situation other than that to meet which the 
instinct was evolved. Plays are instincts applied, in 
advance of their actual need, to situations similar to those 
that will demand their application. The fighting plays of 
boys, and the playing with dolls and at housekeeping of 
girls, are both sets of activities which will be called into use 
later. In these games what is instinctive is not so much 
the motor response as it is the pleasure that comes in think- ~ 
ing and acting out the situation. There is an instinctive 
pleasure in fondling, and dressing the doll : but it is a ques- 
tion whether the doll would evoke the instinct unless it were 
thought of as a child. Not the instinct but the imaginative 
transformation of the doll into a child, and the change of 
the situation as a whole into the home situation, constitutes 
the essential of the play experience. This setting changes, 
and the reaction with it. The doll may be thrown down 
or hidden in a basket when the game is over, as a real child 
would not be. It is a child only while the game is on. This 
make-believe, with the changes in the character of the 
assumptions with changing attitude, is what is at the bottom 
of the play motif. It makes it possible for the child to act 
out situations which are pleasant to him, which he is not 
able to attain in reality. 

The games give opportunity for the expression of the 
various instincts. In addition to the household games 
that are indulged in mainly by the girls and which are 



444 FUNDAMENTALS OF PSYCHOLOGY 

pleasant because of the appeal to racial instincts, we have 
games of contest, which may permit expression of the 
primitive fighting instincts, or the plays of skill, which in- 
dulge merely the instinct of rivalry, in its varied forms, 
coupled with the pleasure in acquirement of skill for skill's 
sake. Any game or instrument which increases capacity, 
which gives a chance for a struggle with possible assurance 
of superiority over some one else, is pleasant. The over- 
coming of danger, the accumulation of real or imaginary 
valuables, as in games of chance, are pleasant because of 
the appeal to the individual instincts. The games that 
involve rivalry and the use of instruments that increase the 
power of the individual, give a satisfaction because of appeal 
to the sense of individual importance, and may therefore 
be classed under the games that appeal to the social in- 
stincts. In practically every case the pleasure of the 
game is instinctive, but it is always itself a product of the 
imagination which constructs a situation representing some 
other real situation that would evoke the instincts in 
question. 

Revery 

Day-dreams Involve Instinctive Elements. — The same 
general statements may be made of revery or day dreaming. 
In the revery, one spends time in permitting the construc- 
tion of situations in idea that would be pleasing were they 
present in reaUty. Some of these constructions are real 
plans for the future. Many, however, are nothing more 
than play ideas, in which one thinks merely how pleasant 
it would be if the imagined constructions should come true. 
One is pleased by the mere passing of the ideas and has no 
thought of attempting to make the desired or imagined 
situation real. Constructions are pleasing because they 
put the individual into situations where he could satisfy 



REVERY 445 

his instincts. He thinks of himself as rich beyond any 
degree that his status warrants as possible; he thinks of 
himself as writing books that would give him renown; he 
pictures himself as doing deeds of valor on the battle field; 
or of rescuing beautiful ladies who shall reward him with 
their love. Self-aggrandizement, success, social appreciation, 
are all his, in his reveries. They satisfy the same instincts 
and impulses as do his games, aside from the desire for 
actual physical exercise and the relief of tension that is 
derived from motor activity. Like play, it is a process of 
make-believe; but the make-believe is limited to ideas, it 
does not extend to action. 

Control of Revery. — We may assume that the course of 
the ideas is determined by the laws of association. Each 
idea that appears and each object that is seen starts a 
series of ideas, by the mere spread of the impulse to the 
other neurones that have been connected with it. As a 
rule mass dissolves into mass in the process ordinarily called 
association by similarity. Pictures of considerable com- 
plexity succeed each other as wholes. The explanation for 
the succession is the connection formed between elements, 
just as it is in all recall. There is some degree of control 
of the recall through the attitude and wider mental settings. 
The succeeding ideas are in large measure congruous • they 
all tend to the development of a consistent whole, although 
the purpose may be httle in evidence when the construction 
starts its course. The idea that shall follow a given idea is 
determined by the wider setting, the objects round about, 
and the ideas that have gone before. It is an instance of 
controlled association, although, as is usual, the control 
is not in evidence. 

The factors most evidently lacking in imaginings of this 
type are the selection processes which pass upon the results 



446 FUNDAMENTALS OF PSYCHOLOGY 

in both reasoning and memory. In memory, the products 
of association are recognized, and if they are not recognized 
as having been present before, they are rejected, and new 
recall is encouraged by supplying new stimuli to the asso- 
ciation processes. One thinks back to the point where one 
left the main track of recall, and waits for something else 
to be suggested, or one looks about for some object that will 
suggest the idea desired. In reasoning, as we have seen, 
there is also a definite purpose, and one waits for the con- 
struction to appear which can be believed to fulfill or satisfy 
the purpose; the suggestions are sometimes as little con- 
trolled as in imagination, but there is always selection from 
the numerous ideas that present themselves of those that 
fit the conditions. 

Selection in Revery is through Instinct. — In the revery 
the ideas are seldom controlled in their course, and there is 
Httle selection. The only choice exerted is in not permitting 
one's self to dwell on the uninteresting. When uninterest- 
ing ideas appear for too long a time, one will either start 
a new train of thought or go to work. The interesting, how- 
ever, is not necessarily pleasant. As will be seen, we occa- 
sionally enjoy picturing ourselves in adversity, and as over- 
come by the thrusts of an unkind fate. One usually pictures 
one's self as overcoming the obstacles and rising to new 
heights, but one seems at times even to enjoy representa- 
tions of one's own misfortune. Reveries, from the stand- 
point of association, are mere trains of thought that run 
their course with a minimum of control in accordance with 
the simpler laws of association, subject only to the veto 

of the boresome. 

The Unconscious 

Freud's Theory of the Unconscious. — In connection with 
this and all of the other forms of imagination, from dreams 



THE UNCONSCIOUS 447 

to humor, we should mention the theory of Freud, which 
has been attracting the attention, particularly of the physi- 
cian, for the past two decades. For Freud, the explanation 
of any mental operation that is strongly emotionally toned 
is to be found, not in the laws of association which we 
have emphasized throughout, but in the work of what he 
calls the subconscious or unconscious. According to Freud, 
one must recognize two levels of consciousness or mind: 
one we have been studying so far; the other lies hidden 
below that, and is not open to observation by the individual. 
Its action can be inferred, merely, from the nature of the 
mental processes and the behavior of the individual. The 
desires of the subconscious are the primitive ones deter- 
mined by instincts. They are opposed by what he calls the 
censor, which corresponds pretty closely to what we have 
been calling social pressure, the influence of social conven- 
tions and ideals which will not permit the ideas of Knes of 
conduct suggested and determined by these instincts to rise 
into consciousness. Freud goes so far as to picture the 
unconscious as a person, Kke the conscious self as a whole, 
which has definite desires, and also can seek different means 
of accomplishing the desires, some of which are very much 
like reason. We are to think of mental hfe as a struggle 
between two persons, one impelled altogether by instincts 
in the desire to gratify the individual — and in Freud's 
theory particularly the racial instincts; while the other 
lives a life of convention, in accordance with the rules of 
good form. The latter is the conscious life, which knows 
its own ends; the former is always concealed, and while its 
aims are known to itself, presumably, they never appear 
above the threshold. The upper, conventional mind is the 
mind we know, or are presumed to know; while the hidden 
motives come mostly from the subconscious. 



448 FUNDAMENTALS OF PSYCHOLOGY 

Dreams 

Freud's Theory of Dreams. — The appKcation of this 
theory is seen most completely in the explanation of 
dreams. Dreams, for Freud, are always attempts of the 
unconscious to force its desires upon the upper conscious- 
ness. Possibly it would be more in accordance with the 
spirit if not the letter of Freud to say that they are a means 
by which the man as a whole enjoys the thoughts, desires, 
and memories which are usually the perquisite of the sub- 
conscious alone. It seems at least that were the enjoyment 
limited to the subconsciousness, it might receive quite as 
much satisfaction in dwelHng on the desires, or revelling 
in forbidden memories alone, and would have no reason to 
share them with the upper, apparently unwilKng, Puritani- 
cal over-lord. Whatever the incentive, the Freudians assure 
us that dreams are vehicles of the thoughts and desires of 
the unconscious. 

But even in sleep the censor is not altogether off guard, 
and in consequence it is necessary to outwit it by various 
stratagems. All dreams are asserted to be suppressed 
wishes. When the wishes are distasteful, the dream actually 
expresses the opposite of one's real desire, or the dream is 
clothed in symbols, which seem innocent, but which the 
unconscious understands to be really sexual in meaning. 
It is asserted that the joy which the upper consciousness, 
which does not understand the symbolism, obtains is a 
vague reflection of the dehght of the unconscious. It should 
be added that Freud insists that the dream usually starts 
from or is suggested by an event of the preceding day, which 
serves to recall some experience of childhood which made 
a strong impression because of its emotional content. For 
Freud, these experiences are always sexual in character, and 



DREAMS 449 

hence always hide behind symbols. It should be said that 
many Freudians widen the meaning of the sexual to include 
other closely related instinctive activities and feehngs, an 
extension which obviates certain of the difficulties we have 
emphasized. 

Interpretation of Dreams. — The difficulty in inter- 
preting the dream Hes in the fact that it may either be a 
wish directly expressed, or the reverse of the real wish, 
or it may mean something altogether different, that can 
be determined by reference to the symbolic relations known 
by experience to the physician. If, for example, one dream 
that a friend is dead, it may mean either that one really 
wishes he were dead, or by opposites, that he should enjoy 
renewed and abundant health. Since for Freud many 
common objects have a symbolic meaning, and all mean 
something sexual, it is always easy to interpret the 
dream as meaning what the interpreter wishes it to mean. 
A serpent, a flower, a landscape, a room, falling, are for 
Freud all sex s3Ambols. Obviously it is somewhat disquieting 
to tell dreams to a convinced Freudian, as some of the 
accepted means of interpretation would be sure to make 
possible a sexual interpretation. 

Dreams Explained by Association. — The alternative 
interpretation of dreams is that they are mere association 
processes, which run their course without the usual controls. 
Ordinarily the dream starts, as Freud says, with some 
stimulation left over from the day before. This suggests 
ideas from the more or less remote past, as Freud asserts, 
but we may assume that the ideas that come are aroused 
by the ordinary laws of association. 

Dreams may be initiated by external stimuli. Cold 
water appHed to the face may produce a dream of being 
out in a snow storm, or more complicated constructions. 



4SO FUNDAMENTALS OF PSYCHOLOGY 

Professor Shepard reports that in an experimental investiga- 
tion of the circulation in the brain during sleep, the patient 
showed marked changes in the volume of the brain as 
men passing spoke outside the window. The patient was 
awakened by the experimenter, and reported a lengthy 
dream of an experience at a party. Numerous similar in- 
stances are on record. Freud insists that the external 
stimulus in these cases serves to arouse the repressed experi- 
ences only, and that the main content of the dream is 
supplied from the subconscious. On the other explanation, 
the sensations would arouse associations that would follow 
their normal course, but a course that was not checked or 
controlled by knowledge as in the ordinary waking state. 

Condensation in Dreams. — All psychologists agree that 
dreams are much condensed. They are merely hinted at 
or represented by the content of the dream. When re- 
called they are much elaborated. Freud would make the 
condensation even greater than the other workers, for he 
believes that the dreamer is not aware of many of the 
meanings that are implied, but that these must be supplied, 
if at all, by the physician who interprets the dream by 
symbolism. Each object has some hidden meaning which 
can only be elaborated by one who knows all the significance 
of the symbols. In addition, the important parts of the 
dream are likely to be displaced, so that they are made to 
occupy a much less prominent place than they should have, 
in the interest of throwing the consciousness off the scent. 
Both condensation and displacement are according to Freud 
means of concealing the real meaning. The truth is not 
recognized by the dreamer even in his most complete in- 
terpretation or reproduction of the dream. Havelock Ellis 
and most other writers who are not Freudians, on the 
other hand, believe the condensation to be a short-hand 



CRITIQUE OF FREUD'S THEORY 451 

representation, for which the dreamer holds the key, and 
which he elaborates in his recall without knowing that the 
dream was in short-hand. 

Other Experiences of the Unconscious 
AND A Critique of Freud's Theory 

Freud's Theory of Revery. — If one transfer the Freudian 
explanation of dreams to the day-dream and ordinary 
revery, it would hold here, too, that the imaginary con- 
struction was the expression of the subconscious, and that 
the material of the day-dream, particularly of those parts 
that give the most pleasure, are to be interpreted by sym- 
bols as meaning what they do not seem to mean. It is 
probably true that some of our day-dreams are the expres- 
sion of wishes; hardly likely, however, that these wishes' 
are often concealed under the form of contraries. Freud 
would have certain of them run as symbols, still more take 
the form of expression of a desire under its opposite, so that 
one would build elaborate constructions in which one came 
off second best, or would think of misfortunes befalling 
members of one's family, when one was really enjoying 
thoughts of triumph. One may at least say that the dream 
and the day-dreams have the same explanation, even if 
one does not decide whether the Freudian or the general 
association theory is the more satisfactory. 

A Critique of Freud's Theory. — The objection to the 
Freudian theory as a whole lies first in his general con- 
ception of the unconscious. One cannot know what there 
is in the unconscious, because by h5Apothesis it is altogether 
removed from observation. It is, furthermore, undesirable 
to give explanations in terms of assumptions that cannot 
be verified. Again, the Freudian explanation is so general 
that it appUes to everything and therefore to nothing. 



452 FUNDAMENTALS OF PSYCHOLOGY 

It is just as much a question why the unconscious should 
desire to dwell on sex matters, or why it should desire to 
forget certain events, as why the conscious should have the 
same attitude or desire. There is no chance for a specific 
explanation of any of these mental events when once they 
are put in the unconscious. Were there any certainty that 
the unconscious existed, these lacks would not prove fatal. 
But as long as we have no absolute evidence of its existence, 
and there is no particular advantage in assuming it, the 
assumption seems uncalled for. A more serious logical 
difficulty with the Freudian explanation arises from the 
very ingenuity of the theory of symbols. The symbols 
include practically all of the objects that commonly appear 
in dreams, and they all symbolize the same experiences. 
If all dreams signify the same thing, and that thing is some- 
thing that sooner or later is bound to enter into the experi- 
ence of any individual, it seems to follow that the assump- 
tion is proved. When one attempts to show from this that 
the ideas are really symbols, the proof is absolutely incon- 
clusive. It amounts to nothing more than reasserting the 
assumption, and then stating that every one dreams in 
symbols. Brilliant as is the hypothesis, one cannot regard 
it as established or capable of being established. It has 
proved of practical value in suggesting means of treating 
patients, but it cannot be highly esteemed as an explanation 
of mental operations. 

Freud's Theory of Forgetting. — The Freudian theory 
has been extended to explain many other phenomena, 
in the individual and race. Freud asserts that the dis- 
inclination of the unconscious to face certain facts explains 
many cases of forgetting. When a man forgets an errand, 
it is because the errand is really distasteful to the dominat- 
ing subconscious. One forgets the present intended for 



CRITIQUE OF FREUD'S THEORY 453 

the individual whom one does not Hke, but to whom one 
feels under obligation. The names of individuals one does 
not like are forgotten, even when they have been frequently 
repeated and should be thoroughly learned. Similarly 
Freud would explain accidents in which objects are dropped 
and broken as due to a real desire to break the objects. 
He instances a case in which he had broken a vase in 
handling. On thinking back he found that the vase 
was a present from a person whom he disliked, and he 
believed that the unconscious broke the vase to remove 
a reminder of the disHked individual. This he regards 
as typical of accidents, just as forgetting the disagreeable 
through the intention of the unconscious is typical of for- 
getting in general. 

Freud's Theory of Wit. — Not all of the activities of 
the unconscious are undesirable. Witty remarks Freud 
would ascribe altogether to the unconscious. Wit always 
has a bitter element in it. This he asserts is not intended, 
nor is the probable effect seen by the speaker. The un- 
conscious, with its usual malevolence, wounds the vic- 
tim when the upper consciousness might be well disposed 
to him, or at least unwilling to offend the conventions 
which prescribe considerate treatment for all with whom 
one comes into contact. 

Symbolism in Myths. — The symbols of the unconscious 
have been extended to explain all of the myths of the race. 
Here the explanation offered by Freud is that the folk 
mind would dwell by preference upon sex matters, but 
conventions which develop (their development is not de- 
scribed) prevent the formulation of these stories of deepest 
interest in direct form. In consequence the early bards 
and men of olden times who formulated the folk tales took 
advantage of the device of expressing the ideas in sym- 



454 FUNDAMENTALS OF PSYCHOLOGY 

bolic form, and the psychoanalyst alone has been able to 
interpret the real truths which they contain. It is interest- 
ing to ask how and why the symbols took the exact form 
that they are assumed to have taken. Jung has suggested 
that they in some way became part of the inheritance of 
the race and have been handed down through the uncon- 
scious in the same way that the instincts are transmitted 
through the physiological organism. 

The whole belief in symbols is one of the least satisfactory 
phases of the Freudian hypothesis. There is no way of 
verifying the hypothesis, because the unconscious can give 
no direct report. The only excuse for the assumption is 
that in the treatment of hysteria a patient will now and 
again report a dream or a day-dream, and when the physi- 
cian has assumed from the theory of symbolism that there 
must have been some repressed or forgotten sexual experi- 
ence, he has been able to confirm its existence, by psycho- 
analysis. This confirmation is less satisfactory than it 
would be if any of the symbols meant anything other than 
sex in some of its forms, or if the physician who believed 
in Freud would under any circumstance be satisfied with 
anything other than sex memories as a cause of the 
disease. It is also difficult to see what pleasure could 
have been found in myths whose symbolism had re- 
mained undiscovered until thirty centuries after the orig- 
inal formulation. 

Art 

Art as Play. — In one of its aspects all art is to be re- 
garded as a form of play. The novel and the drama are 
day dreams of the author which by their character are 
instinctively pleasing to the reading or theatre-going public 
as a whole. The stories that please are, as a rule, stories 



ART 455 

which represent the hero in activities that it would please 
us to share. We can sympathize with his victories, and 
with his defeats which are nearly always temporary and 
which give zest to the final triumph. From the more in- 
tellectual side they may be considered as studies of the laws 
of human conduct, as a result of making certain assumptions 
and determining what the natural outcome must be. In this 
sense a novel or a drama is a depiction of the laws of human 
action, which permits the author to show what a man must 
do under a series of circurnstances, where these circum- 
stances can be worked out free from the many unknown 
forces which are constantly interfering with the action of 
the known conditions in real life. This intellectual interest 
may lead one to find pleasure in the unpleasant ending, 
thus making tragedy vie with melodrama in appeal. 

Sculpture and painting gain part of their appeal from 
the fact that they put day-dreams in form, and represent 
the pure conditions of form in a way that frees them from 
the accessory chances of real Hfe. In part they have an 
appeal from the representation of the forms that have a 
native or instinctive beauty. This beauty may come 
from association with other events or objects that are them- 
selves pleasing; as the proportions of the human body 
seem to be repeated in many of the structures that please 
but which do not even suggest the human form. It may 
be that certain forms have a native attraction, with no 
need for association to intensify the pleasure that comes 
from them. Our purpose here is merely to indicate that 
art has in it certain of the elements of play, in so far as it 
is a representation of one phase of Kfe under the assumption 
that it is the whole. This make-believe unites all forms of 
art with play, as with the day-dream. 

We may mention the explanation of the Freudians that 



4S6 FUNDAMENTALS OF PSYCHOLOGY 

art, too, is a form of symbolism in which comparatively 
innocent terms, forms and ideas represent the sex factors. 
The primitive symbols are applied to novels, to paintings, 
to sculpture, in exactly the same way as to myths. Pos- 
sible illustrations readily suggest themselves. For the sake 
of completeness we may assert that the Freudians find the 
symbols of the dream life embodied in many of the forms 
of art as in the myth. The method of proof is the same as 
that for the other applications, in the similarity or fancied 
similarity between objects depicted in art and the symbols 
of the dream and myth. 

General Remarks on Imagination 

We see, then, that the dream, the day dream, or revery, 
play, and all the creative arts — in particular, the novel 
and drama, painting and sculpture — have many character- 
istics in common. All find their justification primarily in 
the fact that they please, all are largely random activities, 
controlled only so far as they lead to a pleasant end, but 
an end that is not foreseen in advance. All alike, again, are 
processes that are indifferent to truth. They are supposed 
to reach conclusions that are at most but partially true; 
although in art, by pressing home what is true under certain 
assumed conditions, they may enforce truths that could 
not be presented in the more compHcated reahties of Hfe. 
The results are pleasing because they harmonize with the 
instincts; and because on the intellectual side they often 
present the solution of real problems in a way that would 
not be possible theoretically. 

One explanation of the causes that lead them all to take 
the course they do has been found in the laws of asso- 
ciation, the mere connection of neurone with neurone, on 
the nervous side, controlled by the wider interaction of 



GENERAL REMARKS ON IMAGINATION 457 

large masses of the cortex in checking the elements which 
do not harmonize with the whole and in furthering the 
activity of those parts that do harmonize. As in all as- 
sociation processes, we do not know what is coming before 
it comes. At the most the individual knows what the 
general end of all the thinking may be or what he would 
Hke it to be. If he knew more it would not be necessary 
to think. 

As an alternative explanation of the course of these play 
types of thought, we have the assumption of Freud that 
they are results of definite intention on the part of the un- 
conscious. This unconscious we none of us know directly; 
and did we know it, we would have once more the problem 
that we have with the conscious as to why its thought pro- 
cesses act as they do. Were it possible to know as much of 
consciousness as we are assumed to know of the unconscious 
we would have no occasion for the hypothesis that the 
latter exists. If we were to assume the latter, we would 
need the same study of the laws of succession of its ideas as 
that which we have given of the association processes, if 
the explanation is to have any value; for an explanation, 
a study of the laws of connection and of their controls is 
essential. It is better to unify them and explain them 
all in terms of a single self, than to assume a second self 
which would in its turn require the corresponding explana- 
tions. There is no sufficient reason for behef in an 

unconscious. 

REFERENCES 

Constance Long: Psychology of Phantasy. 
Freud: The Interpretation of Dreams. 
Freud : Psychopathology of Everyday Life. 
Rivers: Instincts and the Unconscious. 
Woodworth: Psychology. Chapter XIX. 



CHAPTER XV 
FEELING AND AFFECTION 

The first of the processes that are in part explained and 
in part presupposed in instinct, is feeHng, the tone that 
colors very many of our mental states. The principal 
difhculty in the discussion of feeHng lies in the fact that 
the term has no exact and definite meaning, or perhaps 
more truly has a number of meanings, no two of which 
are altogether reconcilable, and which are held by different 
men of nearly equal authority. The term 'feeling' was 
originally used to indicate approximately the same mental 
states as sensation. We still use the term popularly as 
synonymous with the sensations of touch and with organic 
sensations. It is also used to indicate any conscious state 
which is relatively vague, for example, to designate intuition 
as opposed to the more expHcit ways of reaching conclusions 
by reasoning. We also use the term technically for any 
less definite conscious state. Thus, we talk of a feeling 
of interest, a feehng of recognition, a feeling of behef, and 
many similar states. These states are definite enough as 
ways of being conscious, but their conditions are less in 
evidence than those of sensation. The term ' feeHng ' is used 
popularly and at different times has been used technically 
for a number of different processes which have nothing in 
common except their vagueness, either in the state itself, 
in its reference, or in its conditions. 

Definitions of Feeling and Affection. — Evidently we 
cannot use the term in all of the ways enumerated, and 

458 



FEELING AND AFFECTION 459 

we are the more justified in restricting it by the fact that 
there is a fair consensus of opinion among psychologists 
who have written recently that we shall use it to designate 
a single process or pair of processes commonly known as 
pleasure and pain, or more accurately pleasantness and 
unpleasantness. Since the bare feeHng is never found 
alone but is always accompanied by sensation, it is neces- 
sary to distinguish the simple element from the complex 
of sensation and feeling. Thus, in a headache there is a 
definitely localized sensation or mass of sensations, and 
in addition we dislike the ache. The dislike itself, or the 
form that it takes as a mental process, is the affection, the 
unpleasantness. No one would deny that this is quite 
different as a conscious quality from the sensation itself. 
This quality with its opposite is what is defined as ajfection. 
The complex of affection with sensation is known as a 
feeling. Psychologists thus distinguish affection from 
feeling for their technical usage. Affection is the bare 
fact that we find an event pleasant or unpleasant, while 
feeling is used to indicate the complex of sensation and 
affection. Thus, in the instance above, the mere un- 
pleasantness of the experience connected with the headache 
is the affection, while feeling is the term applied to the total 
experience. What is meant by this state can be understood 
by all, but can be accurately defined or described by no 
one. In the attempt to make clear what is meant, we must 
recall what was said concerning concepts. What we desire 
to do is to indicate a concept, which, together with the 
concept of sensation, shall serve to make possible a de- 
scription of the most general phases of our conscious life, 
and to which we may refer concrete states as they present 
themselves. To make this reference is all that can be done 
in the way of analysis, and it is helpful in all descriptions 



46o FUNDAMENTALS OF PSYCHOLOGY 

and discussions. Sensations or affections are said to be the 
elements of consciousness, but that does not mean that 
they are ever found separately. All that is meant is that 
it is possible to discover in mental states a sensational 
phase and an affective phase, — that certain states are 
similar by virtue of the fact that they are pleasant, just 
as certain others are similar by virtue of the fact that they 
are green, and still others in that they are square. For 
convenience, then, we have spoken of sensations as inde- 
pendent existences and shall speak of affections in somewhat 
the same way, as if affections were elementary conscious 
states, and that mental states might be compounded out 
of them as substances are compounded out of chemical 
elements. 

Affection 

Affection and Sensation. — In justifying a separate dis- 
cussion of the affective phase of consciousness, we must 
meet two objections. First, it has been held that feeling 
is only a special kind of sensation; second, that affection 
is not a distinct element at all but merely an attribute or 
accompaniment of sensation. 

Affection not a Special Kind of Sensation. — In answer 
to the first position it should be pointed out that affections 
are unlike sensations in that they have no special sense 
organs. Pleasure may come as the result of the stimulation 
of any sense organ, and displeasure similarly may be the 
accompaniment of many different kinds of stimulations 
and may be excited through many different sense organs. 
The argument for the specific sensations of pleasantness 
and unpleasantness seems to have been developed on the 
assumption that pain and unpleasantness are identical. 
As we have seen, there is a special sense organ for pain in 



AFFECTION 461 

the skin and other tissues, and if pain and unpleasantness 
are to be considered identical, the sense organ for both is 
readily supplied. As a matter of fact pain and unpleasant- 
ness do not mean the same thing. Pain is the specific 
sensation, and unpleasantness the accompanying reaction. 
One may see this most clearly, perhaps, from the fact that 
pain is not necessarily unpleasant. Without speculating 
as to the pleasure of martyrs, we find numerous cases in 
which slight stimulation of pain spots is pleasant, as in the 
cold of a bath, or the fascination of pressing gently upon 
an inflamed spot. While pain in shght intensity may on 
occasion be pleasant, it is not at all infrequent for un- 
pleasantness to accompany other mental processes in which 
there is no excitation of a pain nerve. Smells are unpleasant 
when there is often none of the sharpness that represents 
the excitation of cutaneous sense ends. The odor of decay- 
ing flesh is unpleasant in itself, as opposed to the unpleasant- 
ness of ammonia or chlorine, which is in part due to the 
excitation of pain nerves in the mucous membranes of the 
nasal passages. Unpleasant combinations of colors or of 
tones belong in the class of experiences unpleasant in them- 
selves, as do also the unpleasant effects derived from 
unpleasant spatial and temporal relations, the unpleasant 
ideas from social wrongs, etc. One finds a long list of 
unpleasantnesses that cannot be referred to sense pains. 

If pain be not identical with unpleasantness, and the 
pain nerve be not the organ of the unpleasant affection, 
still less is it possible to find a specific sense organ for 
pleasantness. It has been suggested that tickle may be 
the pleasant quality, and that there is a specific sense organ 
of tickle. This latter statement, however, is very question- 
able. Tickle spots have now and again been reported, 
but the report has seldom been confirmed, and has never 



462 FUNDAMENTALS OF PSYCHOLOGY 

been generally accepted. Granted the existence of the 
tickle spots, the same objections hold to identifying tickle 
with pleasure as to identifying pain with unpleasantness. 
Tickhng may be unpleasant and many different kinds of 
pleasure have no resemblance to tickling. Evidently even 
if we grant the existence of the tickle spots, pleasure must be 
something more than a pecuhar cutaneous sensation, just 
as unpleasantness is distinct from and in addition to pain. 

Affection is not Localized. — Other objections to identi- 
fying affection with sensation may be made on the basis 
of the lack of accuracy of locaHzation of the affections. 
Sensations always have a definite place, while affection is 
not definitely locaHzed. One is displeased or pleased in no 
particular part. Exceptions have been taken on the basis 
of organic sensations, but organic sensations are rather 
incorrectly localized than unlocaKzed. Another distinction, 
which rests on a slightly less certain basis but is probably 
generally valid, is that sensory processes are more objective 
while the affective processes are more subjective. Sensa- 
tions usually are referred to the outside world, while 
feelings are pecuHarly personal, peculiarly one's own. 

Affection and Attention. — Closely related to this are the 
differences with reference to the effects of attention and the 
influence of recall. It seems fairly well assured that attend- 
ing to a feehng tends to diminish rather than to increase it, 
while, as was seen, attention increases the effectiveness of 
sensations. In passing upon this statement, one should 
be careful to distinguish between attending to the stimulus 
or to the sensation, and to the mere accompanying pleasant- 
ness or unpleasantness. If one think of an aching tooth, 
the pain is increased and the accompanying unpleasantness 
with it. If, however, one attempts to introspect, to ask 
how and why this sensation is unpleasant, one will be 



AFFECTION 463 

likely to find that the unpleasantness diminishes as one 
becomes interested in watching the feehng, and it may 
disappear altogether. An unpleasant situation bravely 
faced tends to lose much of its unpleasantness. The same 
may be said of pleasantness. In practice, a constant search 
for pleasure defeats its end. A pleasure attended to tends 
to diminish. Lives spent in pleasure-seeking seem never 
to attain their goal. The only way to make sure of pleasure 
is to keep in mind some end to be accomplished and let 
the pleasure come as an incident to its attainment. Keep- 
ing pleasure itself in mind destroys it, while attending to 
the stimulus increases pleasure as well. The objective and 
subjective difference may be said to be one phase of this 
influence of attention. Objective processes, when attended 
to, increase; while a purely subjective process, particularly 
if that be related in some way to attention itself, would not 
be increased. If one think of feeling as an effect of attend- 
ing to a stimulus, it would follow that when attention was 
not fixed upon a stimulus, at least one condition of feehng 
would disappear, and the feeling with it. 

An Affection is not Recalled. — This subjective character 
of feeling has also been connected with another character 
or alleged character of feeling, namely, that it cannot be 
remembered. It is asserted with some warrant from obser- 
vation that feelings are not recalled. This statement must 
be carefully guarded and restricted if it is to be accepted. 
The warrant for it is to be found in the fact that feelings 
toward an event are Ukely to change between the time the 
event is experienced and the time it is recalled. Thus a 
social faux pas that caused extreme embarrassment may 
later arouse only amusement, and a practical joke that was 
much enjoyed at the time may be recalled with chagrin. 
The affection alone is not recalled in these cases, but the 



464 FUNDAMENTALS OF PSYCHOLOGY 

event is recalled, and the feeling aroused depends upon the 
circumstances at the moment of recall. This does not mean 
that one cannot remember that one was pleased or dis- 
pleased on the first occasion; one remembers the fact, but 
the affection is not reinstated. The memory of how one 
felt is indirect, is in terms of words or the memory of the 
expression. The feeHngs are not reinstated as the sensory 
elements may be, but are merely represented or meant. 
The feeling at the time of recall is the expression of the 
present attitude toward the event rather than of the earlier 
attitude, the attitude when the event was really experienced. 

Altogether there seems little probability that affections 
are merely separate sensations. Pain and unpleasantness 
are distinct, and pain seems to be the only sensation which 
could in any degree be confused with either pleasantness 
or unpleasantness. Pleasant sensations have no existence; 
i.e., there are no sensations to which the term pleasant- 
ness could always and regularly be applied that do not 
have a distinct sensation quality in addition. To as- 
sume that any of these sensations could be regarded as 
identical with the feeling quaUties is out of harmony with 
the facts of distribution, as well as with the quaUties of both 
sensation and feeling. The more definitely qualitative 
differences, the different influence of attention, and the 
difference in the way they are affected in recall, all reenforce 
this conclusion. 

Affection not an Attribute of Sensation. — The second 
position in criticizing the separation of affection from sensa- 
tion — that affection may be an attribute of sensation — 
meets with just as grave difficulties. As Kiilpe has sug- 
gested, it is always true of attributes that when one vanishes 
or is reduced to zero, the sensation also disappears. Sensa- 
tions with no affective tone are, on the contrary, relatively 



AFFECTION 465 

common. A sensation may be indifferent and still be a 
sensation, while a sensation that has no quaHty and no 
intensity ceases to exist. Furthermore, affections have 
attributes of their own which vary independently of the 
attributes of sensation, which again is inconsistent with the 
assimiption that affection is merely an attribute of sensa- 
tion. Affection has duration, intensity, and quality, is 
unpleasant or pleasant, although it has no extent or posi- 
tion. On the affirmative side of the question, it must be 
granted that we apparently never have affection without 
some sensation, and so it is not an entirely independent 
entity. One never feels vaguely pleased or displeased: 
there is always some sensation as the occasion for the affec- 
tion. In certain instances the affection seems the dominant 
element in consciousness, but slight observation indicates 
that there are also sensations, usually of a vague organic 
character, that serve as the excitant of the feeling. But, 
as has just been said, this same sensation may at times be 
present in some degree without any accompanying feeling 
or, on occasion, with a feeUng of the opposite character. 
On the whole, it seems fairly safe to conclude that the quah- 
ties of pleasantness and unpleasantness are found in close 
dependence upon stimulus and sensation, but nevertheless 
constitute what may be regarded as an independent mental 
state, or, to speak more conservatively, as a phase of 
consciousness which cannot be understood if we regard it 
as merely sensation, or as an attribute of sensation. 

Treating our topic from the structural point of view, 
affection constitutes a type of mental process distinct from 
sensation but nevertheless dependent for its existence upon 
sensation, certainly upon the excitations that cause sensa- 
tions. Pleasantness and unpleasantness come as a result 
of sensory excitation immediate or recalled, and these 



466 FUNDAMENTALS OF PSYCHOLOGY 

excitations produce sensations at the same time or a little 
before they give rise to the affections. It is probably true 
that no excitation gives rise to an affection without also 
arousing a sensation. The occasional periods of vague well- 
being or vague ill-being without apparent sensational basis 
are rare, and in all probability are merely cases in which 
the affective aspect of consciousness has for the moment 
overshadowed the sensory. While affection is thus depend- 
ent upon the same excitations as sensations and even prob- 
ably dependent upon the sensations themselves for its exist- 
ence, it is not a mere attribute or phase of the sensation, as 
are quality and intensity; rather we must regard it as a 
separate mental state or process with attributes of its own. 
Qualities of Affection. — Starting from this assumption, 
we may consider affection in its relation to the various stim- 
uli, enumerate its qualities and its physiological accompani- 
ments, in much the same way as we have treated the cog- 
nitive processes. First, with reference to the qualities of 
feeUng, it may be asserted that there are but two, pleasant- 
ness and unpleasantness. Many objections have been 
raised to this statement. In the first place, as has been seen, 
many people mean altogether different kinds of mental 
processes, intuitions and what not, from those that we have 
admitted into the class. These we may exclude by mere 
arbitrary definition. They certainly have an existence and 
a place in psychology, but fall rather under reasoning and 
other heads than under feeling. They simply are not 
sufficiently like the processes we are discussing to make it 
possible to extend the term to include them. Wundt, using 
the term in somewhat our way, makes the suggestion that 
there are many different qualities of feeling, one for each 
sensation and intellectual process. To this the majority 
of psychologists stand in direct opposition. The differences 



AFFECTION 467 

that strike one are due rather to the quaHties of the accom- 
panying sensations than to the feeHng qualities themselves. 
If one can abstract the sensational elements from a feeling, 
the purely affective remnant is always the same — ^ pleasant 
or unpleasant. 

Pleasantness and Unpleasantness the Only Qualities of 
Affection. — To recognize only pleasantness and unpleas- 
antness as qualities of affection is opposed to many authori- 
ties, ancient and modern, but the distinctions they draw 
seem to be based on other than psychological grounds. 
Thus, the moralist of everyday life draws a distinction 
between higher pleasures and lower pleasures. One is the 
pleasure from the simple senses, the pleasures of eating, 
for example, particularly the pleasures from the satisfaction 
of the simpler instincts, while the higher pleasures are the 
pleasures of the imagination, aesthetic pleasures, the pleas- 
ures from moral acts. In general, they are the pleasures 
which society approves, while the lower pleasures are those 
which are either disapproved or regarded as morally in- 
different. This distinction is recognized by every one. It 
is at the basis of one of Dr. Johnson's favorite distinctions 
between pleasure and satisfaction. Still it is generally 
beHeved not to correspond to any real difference in psycho- 
logical quality, but rather to a distinction based upon 
ethical considerations. Sensuous pleasure is believed to be 
of the same quahty as moral pleasure; the pleasure from a 
pleasant odor, of the same quality as that from a painting 
by an old master. The difference is to be found in the fact 
that one is approved by the connoisseur, carries with it a 
certificate of being beyond the ken of the multitude, and 
takes an added flavor from that fact, a flavor which may 
intensify the other quality but is of the same general class 
or type. Other suggested qualities of pleasant and un- 



468 FUNDAMENTALS OF PSYCHOLOGY 

pleasant seem on analysis to reduce to similar extraneous 
considerations and to leave but two qualities, pleasantness 
and unpleasantness. In general, one must admit with 
Wundt that the total feeling varies with each stimulation 
and with each sensation or memory or other sort of mental 
state; however, the variation is not in the affection but in 
the sensational accompaniments. The pleasantness or un- 
pleasantness is, if we are to beHeve the introspections of the 
large mass of psychologists, always identical; and the dif- 
ferences that Wundt insists upon are to be found in the 
cognitive accompaniments. The differences between sen- 
suous, aesthetic, and moral pleasures or displeasures are in 
the occasions of the affections, in the cognitive component of 
the feeUngs rather than in the affective elements themselves. 

Other Aspects of Feeling 

Other Suggested Pairs of Feelings. — Wundt and Royce 
assert that there are other definite opposites of consciousness 
that must also be classed as feehngs. Royce adds two, 
restlessness and quiescence. The one is said to be charac- 
terized by a constantly changing impulse to movement, 
particularly by a feeling that one must get on to do some- 
thing else; while quiescence implies an assent to the present 
condition, a readiness to remain in the condition in which 
one is. Wundt affirms that there are three pairs of affection 
which may be regarded as constituting a three-dimensional 
series. To pleasantness-unpleasantness he adds strain and 
relaxation, excitation and quiescence. Strain and relaxa- 
tion are related to the feeHng of effort and its lack in atten- 
tion, — strain appears in expectation, relaxation in reaHza- 
tion. Wundt insists that these quahties do not come from 
the contraction of the muscles and their relaxation, but are 
as truly affections without assignable sense organs as are 



OTHER ASPECTS OF FEELING 469 

pleasantness and unpleasantness. Excitation arises when 
one is disturbed through attempting a difficult task, is a 
component of anger and of certain exhilarating forms of joy. 
Quiescence or inhibition is an accompaniment of rest, per- 
haps of lassitude. They, too, are peculiar quahties of affec- 
tion with no sense organs and no definite relations to the 
other forms of feeling. These extra pairs were supposed to 
be accompanied by special physical reactions, but later 
investigators seem to have pretty clear evidence that the 
experiments in support of them were inaccurate or wrongly 
interpreted. On the whole, direct observation seems not to 
bear out Wundt's contention that these forms of conscious- 
ness are feehngs. There can be no doubt that the states 
exist, but they seem to be either directly due to special 
sensations such as the kinaesthetic impressions, in strain 
and relaxation, or to more complicated organic processes in 
excitation and quiescence. These are probably closely 
related to the qualities of the emotional states to be dis- 
cussed in the next chapter. In any case they are not 
affections in the same sense as 'are pleasantness and un- 
pleasantness. 

Intensity of Stimulus and Intensity of Affection. — The 
other attributes of affection call for but brief discussion. 
The intensity of each quality of affection varies from zero 
to a maximum that may end in the loss of consciousness. 
The relation to the intensity of stimulus has been expressed 
by Wundt in a curve that holds for stimuH of certain kinds, 
although there may be exceptions. A faint stimulus is usu- 
ally indifferent. As the intensity increases, a pleasant affec- 
tion begins and increases to a maximum with moderate 
excitations, and then drops to indifference, and finally be- 
comes unpleasant as the excitation is increased still more. 
The point at which pleasantness disappears varies with the 



470 FUNDAMENTALS OF PSYCHOLOGY 

nature of the stimulus. In many cases it is at a very low 
point in the scale of intensities; for other qualities all but 
the highest intensities are pleasant. With suitable allow- 
ances, practically all sense qualities will be found to corre- 
spond with the rule in some degree. It at least approxi- 
mates a law. In the diagram, the Hne a indicates the 
increase in sensation by the logarithmic curve in accordance 
with Weber's law; e, the curve of increase in intensity of 




Fig. g3. — Schematic diagram of the relation of affection to sensation. The 
smooth curve shows the rise of sensation with intensity of stimulus, the dotted line 
the accompanying rise and fall of pleasantness and the increase of unpleasantness. 
(From Wundt.) 

affection — above the Hne indicating pleasant, below the 
line unpleasant affection. The duration of affection differs 
from the duration of the stimulus both at the beginning and 
the end. Affection, as has been said, lags behind the 
stimulus, appears later, a little after the sensation even, in 
most cases, and may either disappear before the stimulus 
or change its tone as the stimulus persists. Thus, stimuli 
which at first are pleasant may become indifferent or become 
unpleasant if they last too long. Duration has much the 
same tendency as intensity in this respect, and one might 



OTHER ASPECTS OF FEELING 471 

draw a similar curve. The tendency is always for the feeling 
to become unpleasant rather than pleasant as its duration 
increases. No general rule can be given even for the same 
stimulus as to how great the duration must be before the 
quality will change. 

Affection and the Qualities of Sensation. — It would be 
highly desirable, were it possible, to give either a catalogue 
or some general law that should classify the objects or 
stimuli that give rise to pleasure or displeasure. We have 
already attempted this for the intensity and duration of 
stimuli. To list the qualities that are pleasant is much 
more difficult. Experimental aesthetics has made the at- 
tempt in certain fields, but the results are too voluminous 
to be presented in detail, and the general summaries are 
too few and too schematic to be very satisfactory. 

Bodily Accompaniments of Feeling. — While one be- 
comes acquainted with feeling primarily through inner ob- 
servation or introspection, numerous attempts have been 
made to obtain some record of the behavior in feeling that 
may serve as a measure of the amount of feeling, or even 
as an indication of the nature of feeling. It is a matter of 
common observation that practically all individuals show 
pleasure or displeasure by certain physical changes. The 
face is said to light up or to lower, and the general bodily 
attitude changes in accordance with the feehngs. In most 
cases the presence of pleasure or its opposite can be read- 
ily and clearly detected by observation. Many investiga- 
tions have been undertaken and carried out to translate 
these simple observations into more accurate measure- 
ments. One of the first series of studies was of the changes 
in respiration and circulation. The first results seemed to 
indicate that there was a definite opposition in these pro- 
cesses corresponding to the opposition between pleasant- 



472 FUNDAMENTALS OF PSYCHOLOGY 

ness and unpleasantness. Thus Lehmann ^ asserts that in 
pleasure respiration is slow and deep ; while in unpleasant- 
ness, at least after an initial inhibition, it is quick and 
shallow. The pulse, similarly, is said to be slow and strong 
in pleasure, and quick and weak in unpleasantness; the 
blood vessels dilate in pleasure, contract in unpleasantness. 
Later investigations by Courtier,^ Shepard,^ and others 
make it quite clear that the effects depend very largely 
upon the strength of the stimuli rather than upon the af- 
fective tone; that all stimuli tend to quicken the respira- 
tion and make it shallow, to quicken the pulse and make it 
feeble, and to constrict the blood vessels. It is altogether 
probable that Lehmann's results with pleasure were due to 
the fact that pleasant stimuli are usually faint, and so if 
there has been strong stimulation just before, the vital 
processes tend to return to normal, and thus seem to show 
changes that are the reverse of the effects of the stimula- 
tion. Wundt and his students have attempted to demon- 
strate peculiar physiological changes of the same sort in 
connection with his suggested pairs of strain and relaxa- 
tion, exaltation and depression; but study of their curves 
indicates that they have l^een misled by similar phenomena 
of recovery, and by rhythmic changes that have no rela- 
tion to the changes in the feeling that they are studying. 

Other Physiological Changes. — Of the other physio- 
logical changes in connection with feeling, the secretion of 
saHva has been studied most extensively by Pawlow. He 
found that it was possible to record from the study of the 
dog many of the changes that result from stimulations 
which in man are accompanied by feeling and even by in- 

1 Lehmann, Hauptgesetze d. menschlichen Gefiihlsleben. 

^ Courtier, L'Annee psychologique. Vol. i. 

3 Shepard, American Journal of Psychology, Vol. 17. 



OTHER ASPECTS OF FEELING 473 

tellectual processes. This he accomplished by dissecting 
out the duct of the sahvary gland in the cheek of the dog, 
and adjusting it so that the saliva might flow into the pan 
of a recording scale. It was found that the sight of food or 
of any object associated with food led to an increased flow, 
and that the amount secreted was a very good indication 
of the mental state of the dog. This corresponds to the 
dryness of the mouth in man in displeasure or excitement, 
particularly in fear, and the free flow of saliva in pleasure 
even when that be not associated with food. The opposi- 
tion between pleasantness and unpleasantness does not 
hold altogether here, again, since any strong excitement, 
pleasant or unpleasant, gives the same dry mouth. 

Somewhat the same statement may be made of the se- 
cretion of tears. Strong grief or displeasure causes weep- 
ing, but the brightness of the eye in pleasure is also due to 
increased secretion of the lachrymal gland which in ex- 
treme pleasure may overtax the tear ducts and flow down 
the cheek. 

Slightly better evidence may be given for an opposition 
in expression in the bodily posture. Grief seems to be 
marked by a drawing together of all the members, while 
pleasure leads to an actual physical expansion, — head 
erect, even thrown back as in laughter, the arms extended 
and the trunk held straight. These general bodily move- 
ments have been much less carefully studied than the 
others, and the opposition of the different kinds of feelings 
shown in superficial observations may disappear upon fuller 
investigation. 

We may assert, then, that the feelings show very marked 
bodily accompaniments, but that these cannot be said to 
correspond accurately to the differences between pleasant- 
ness and unpleasantness, although the degree of our feeling 



474 FUNDAMENTALS OF PSYCHOLOGY 

carries with it an approximately corresponding amount or 
intensity in the accompanying physical expression. The 
expression of the feeHngs merges gradually into emotional 
expression, which must form a considerable portion of the 
matter of the next chapter. 

Theories of Feeling 

Difficulties in Formulating a Theory of Feeling. — In 

attempting to summarize the facts collected concerning 
feeHng and to refer them to a single principle, many the- 
ories have been developed. At present the facts cannot be 
brought to harmonize with any single general statement; 
but, rather, different groups of facts may be brought to 
the support of different statements in themselves not alto- 
gether consistent. While no single theory may be said to 
be true to the exclusion of the others, all taken together 
give a better idea of the nature of feeHng and its relations 
than can be obtained by any mere statement of facts. The 
first element that is lacking in the construction of a theory 
is a satisfactory basis in the nervous system. Each of the 
other fundamental processes has a definite nervous struc- 
ture or activity to which it may be referred, and which 
gives definiteness to the explanation; but affection has 
neither special sensory nerves to provide it a particular 
stimulus, nor special central structures that elaborate its 
materials. Study of pathological cases of disturbances of 
the affective life in the symptoms of melancholia or eu- 
phoria are accompanied, so far as at present known, by 
no peculiar lesions with which the diseased affections may 
be associated or to which they may be referred. So far as 
changes in the nerve tissue have been traced, they are 
widespread and general rather than closely localized and 
specific. It cannot be said that one is pleased or displeased 



THEORIES OF FEELING 475 

in any particular part of the brain or nervous system, or 
that affection is carried by any particular nerve or corre- 
sponds to any peculiar process. 

Physiological Theories. — Of the theories, we may dis- 
tinguish three main groups with several cross hnes of divi- 
sion. One of the oldest and most generally accepted makes, 
pleasure and displeasure the accompaniment and indication 
of benefit and injury to the organism. This takes different 
forms, either as an expression of an immediate change in 
the organism in general, of the nervous system as a whole, 
or of some particular part of the nervous system. It may 
be an indication of what has been good or bad for the in- 
dividual or race in the past and is hkely to prove so in the 
future. For these theories, pleasure means that there is in 
the individual at the moment a process of upbuilding, of 
anaboHsm; that this anabolism is induced in the nervous 
system as a whole or in the frontal lobe, — for Wundt the 
great coordinating centre for all nervous and mental activ- 
ity. The evidence for each of these theories is indirect and 
may be found in the general law that the beneficial is on 
the whole pleasant, that the injurious is on the whole un- 
pleasant. Correspondingly, when one is physically in good 
health, well rested and nourished, many activities and even 
excitations are pleasant which become unpleasant when 
the physical tone is lower. These facts have been inter- 
preted to mean that action of a well-nourished nervous 
system or part of the nervous system means pleasure, and 
that the action of a badly nourished system means dis- 
pleasure. Taken Kterally, the identification of pleasure 
with anabohsm, and displeasure with katabohsm, would 
make all action and stimulation unpleasant, since all ac- 
tion involves use of reserve nutriment. The anabolism- 
katabolism formula has been modified by permitting kata- 



476 FUNDAMENTALS OF PSYCHOLOGY 

bolism within moderate limits, the Hmits of ready recuper- 
ation, to give pleasure. This limit would be difficult to 
determine empirically, however. 

Evolutionary Theory. — Another change in the state- 
ment of the theory permits the formula to mean a general 
benefit or injury to the race in the evolutionary sense. 
This enables one to account for many of the seeming dis- 
crepancies between benefit and pleasure. Thus, it seems at 
first not true, even in general, that the pleasant in food or 
drink is also beneficial. Aside from exceptions, however, we 
do use feehng as a guide to foods. We eat what we like, or 
at least we do not eat what we do not hke. The excep- 
tions apply to excesses or to substances of rare occurrence 
in the environment in which the race evolved. The race 
as a whole is more Hkely to survive if it makes use of 
pleasant but injurious foods, such as sweet poisons, than 
if it ate no sweets. The exceptions must be learned by in- 
dividual experience. It is much better to eat than not to 
eat, in spite of the fact that overeating is harmful. When 
to stop can be learned from the unpleasant symptoms that 
indicate injury. Pleasantness and unpleasantness serve as 
a general guide to conduct, and may be said, metaphori- 
cally, to be the expression in the individual of the experi- 
ence of the race as to what is good or bad. This expression 
is open to many exceptions, is not a final law, but must be 
modified by the experience of the individual and the accu- 
mulated knowledge of the race. It should be added that 
the manner in which the experience is recorded and trans- 
mitted in the individual, and how and why it acts, are not 
at all known. The theory is nothing more than a formu- 
lation of the general group of facts that, in the long run, 
what pleases, benefits; what displeases, harms. 

Furtherance-Hindrance Theories. — Another group of 



THEORIES OF FEELING 477 

theories accounts for the more active pleasures largely 
overlooked in the theories just mentioned. This group 
couples easy running or unopposed action with pleasure, 
diiScult or opposed action with displeasure. In one form 
the theory makes real physical movements the basis, in 
other groups it is taken in a more metaphorical sense. 
Thus, the first theory states that a smooth, graceful curve 
is pleasant because the eye will follow it without effort, 
with a single sweep; while a series of short lines with 
many changes in direction is ugly because of the difficulty 
of the eyes in following them. 

A shght departure toward the metaphorical is seen in 
the theory of 'empathy' (Einftihlung) of Lipps, in which 
the individual does not necessarily have opposed action in 
his own body, but sympathizes with the figure, feels in un- 
pleasantness that he would have difficulty in doing what 
he personifies the figure as doing. 

Finally, we have Stout's theory that one may have op- 
position in the accomplishment of an intellectual purpose, 
in reaching some conclusion in thought; or, on the con- 
trary, one's mental operations may run smoothly or be 
helped, and so be pleasant. In each of these cases further- 
ance or easy action means pleasure, hindrance or inter- 
rupted action displeasure. As before, one may accept the 
general statement, particularly in the metaphorical form, 
although the more specific apphcations offer much room 
for doubt and may be disputed as to facts. 

Feelings Dependent upon Earlier Experiences. — The 
third form of theory attempts to explain how feeling can 
be dependent upon such a wide range of experiences, 
rather than why one is pleased or displeased. The first 
form of this theory is Wundt's statement that feeling is 
the obverse of, or at least one phase of, apperception. For 



478 FUNDAMENTALS OF PSYCHOLOGY 

Wundt, apperception is practically synonymous with the 
active life, covers much of what is treated under atten- 
tion, perception, and will. It is the effect of the entire 
earlier experience of the individual in the control of his 
present action in attending, in interpreting the material 
offered to perception, in thought, and in practical conduct. 
This definition makes feeling an expression of the interac- 
tion between the coordinated earlier experience of the in- 
dividual and the present experience. On the nervous side, 
Wundt gives apperception a seat in the frontal lobe, prob- 
ably in the front portion of the frontal lobe, and so com- 
bines his psychological theory with the physiological in 
the formula mentioned above, that pleasure corresponds 
to the action of a well nourished, displeasure to the action 
of a badly nourished, frontal lobe. This means, or may be 
made to mean, that whether any process is pleasant or un- 
pleasant depends upon the entire accumulated experience 
of the individual and in the way that experience is brought 
to bear upon the process in question, a statement that is 
undoubtedly true, although somewhat vague. If we re- 
place apperception by attention, and consider the nervous 
factors that are found to determine the control of attention, 
we should have approximately the same formula in our 
own terms. 

Summary. — We may assert that feeling is an expression 
of the factors that control attention, an expression of the 
interaction between the instincts and past experience of 
the individual, and the present situation. It is an indica- 
tion of the reaction of the nervous system of the individual, 
as the result of original endowment and individual acquire- 
ment, to the stimuli of the moment. To give an explana- 
tion of pleasantness and unpleasantness this formula would 
need to consider the essential phases of the other two 



THEORIES OF FEELING 479 

theories. The theories are mutually complementary rather 
than exclusive. Thus, the pecuHar reactions that give 
rise to pleasure are indications that the stimuU in question 
have been beneficial; those that give rise to displeasure 
have been on the whole injurious, either to the race or to 
the individual. In the one case we deal with an instinctive 
response, in the other with a response due to individual 
acquirement. In the individual acquirement, association 
with similar experiences or direct connection with other 
experiences, either in themselves unpleasant or pleasant, 
plays a large part. One may have the affection of the 
associated event without having the event itself definitely 
recalled, as can be seen in the dislike of many foods with 
which one has had unpleasant experiences, or a liking for 
colors that have been connected with some very pleasant 
occasion. The feeling comes, in such cases, without nec- 
essarily recalling the event that may reasonably be supposed 
to have occasioned it. Just what the nature of the re- 
action may be that gives rise to feehng, why we become 
conscious in feeling of the nature of the forces that are 
active in controlling attention, we cannot at present say. 
The justification for the theory is the far-reaching de- 
pendence of feelings upon so much of the earlier life of the 
individual. 

REFERENCES 

Titchener: Psychology of Feeling and Attention. 
Marshall: Pain, Pleasure, and Esthetics. 
Warren: Human Psychology, pp. 279-286. 



CHAPTER XVI 

EMOTION AND TEMPERAMENT 

Probably the most impelling and self-asserting mental 
state of all is emotion. For good or for ill it marks the 
greatest disturbance in the course of mental events, and is 
the most personal, the most pervasive. Emotions stand 
in closest connection with feeling and with instinct. From 
the feelings they can be distinguished only by the amount of 
response that accompanies them and by their general com- 
plexity. Unpleasantness becomes anger or fear when 
movements of attack or flight begin, when the muscles of 
the face and of the internal organs grow tense, and give 
rise to sensations. On the other hand, many of the occasions 
for the emotions and practically all of the movements ac- 
companying emotion are instinctive. Emotion may be 
defined by virtue of these relationships either as a com- 
plicated feehng or as the subjective side of the instinct. 
The list of emotions ordinarily given has varied relatively 
little since Descartes, and his list can be traced with com- 
paratively few changes to much earlier periods. His list 
includes: surprise, love and hate, desire, pleasure and dis- 
pleasure; while in Shand, one of the latest writers who 
has elaborated upon the classification, we find : fear, anger, 
joy, sorrow, disgust, wonder, to which McDougall adds 
the more personal quaHties of dejection and elation. These 
are for all authorities the more fundamental emotions. 
The others develop from them by combination, by change 
in intensity, in the nature of the object that arouses them, 

480 



CHARACTERISTICS OF EMOTION 481 

or in the time at which the event that arouses the emotion 
has occurred or is to occur. 

Characteristics of Emotion 

Classifications of the Emotions. — In any discussion of 
the emotions it is essential to consider separately two 
factors: the conditions or causes of the emotions, and the 
mental content and physical reaction during the emotion. 

There are two possible classifications of emotions with 
reference to cause, although the cause does not necessarily 
affect the quality of the emotions. Two general causes 
for emotions have been assigned. One, generally current 
at present, asserts that emotion is merely an instinct seen 
from the inside, that the real cause is to be found in the 
instinctive response. The other, which goes back to re- 
mote antiquity, insists that emotions arise from some con- 
flict between ideals or desires and the momentary environ- 
ment. The first theory applies best to those emotions called 
out immediately by some external stimulus by virtue of a 
fundamental characteristic of the organism. Sudden fear 
at sight of a snake, sudden anger at an injury, the sudden 
glow of love at first sight, all fall in this class. They need 
no explanation other than the inherited nervous mechanism. 

The second group of theories finds its explanation in the 
checking of some general movement or current in the life 
of the individual. In the writings of the older men one 
finds much difference of opinion as to what it was that 
moved, but they agree that all emotions arise from a check- 
ing or facilitation of the movement, and also that unpleasant 
emotions arise from the checking, pleasant emotions 
from the facilitation. For Descartes the obstruction was 
suffered by the movements of the fluid products of digestion 
or the blood ; for Spinoza the movement was of an unnamed 



482 FUNDAMENTALS OF PSYCHOLOGY 

mental force which was pressing towards a goal of hypo- 
thetical perfection. For Shand the impelling force is what 
he calls sentiment, a force derived in part from instinct, 
in part from experience, and in part, perhaps, underived, 
which exhibits systems or groups of forces in ever-widening 
subordinations. These he divides into the three classes: 
love, parental sentiment, and the unselfish or social senti- 
ment. When these sentiments find free play or are assisted, 
pleasant emotions are experienced; when checked or 
thwarted in any way the emotion is unpleasant. "Every 
primary impulse . . . when opposed tends to arouse anger; 
when satisfied, joy; when frustrated, sorrow; and when 
it anticipates frustration, fear." 

The System of Purposes in Emotion. — If one is to 
accept at all this old theory, obviously the first problem 
is to determine what it is that gives rise to the determining 
impulse or sentiment, or, in a more conscious sense, the 
goal of action. As was seen in an earlier chapter, instinct 
supplies the impelHng force, the directing influence, in most 
conscious processes. To instinct are due the fundamental 
tendencies. But upon them is built a great superstructure 
of desires, acquired from education, through living in a 
particular environment, which serves to differentiate the 
aims of the individual from his fellows, and characterizes 
the ideals of the people of one community or social stratum 
or of one country or of one race. The last two mentioned 
are dependent in part upon social instincts which make the 
suggestions and the aims of the group acceptable to the 
individual. The traits common to all are instinctive; 
the more particular result from education. Granted that 
it is instinctive to attain wealth, one must admit that the 
form that wealth is to take varies from race to race, and the 
amount aimed at is different for different social groups 



CHARACTERISTICS OF EMOTION 483 

within the community. Whether one strives for the wam- 
pum or cattle of the savage, as opposed to the bank ac- 
count of modern man, is a question of enviromnent; as is 
also whether one sets one's goal at milhons or thousands. 
Similarly, desire for social approval, for what may be 
caUed fame, is general, perhaps instinctive, but whether 
in athletic skill or scholarship, whether in business or in 
art, in poUtics or war, depends upon early environment 
and even upon chance factors in education. Both the 
sentiments and impulses of instinctive origin and the 
ambitions developed at the more conscious stage must be 
assumed, if emotion is to exist. An individual to whom 
nothing really mattered would be without emotion. The 
presence of a system of aims makes possible the bare 
potentiaHty of emotion; the nature of the aim determines 
the character of the objects that shall excite the emotions. 
The emotion itself is an incident in the struggle for the 
attainment of an end. 

The Qualities of Emotion. — While one may distinguish 
two classes of emotion from the standpoint of instinctive 
purposes which are furthered or thwarted, no corresponding 
difference can be discovered in the qualities of emotion. 
From comparing the qualities of the results, it is impossible 
to say whether anger has been produced by a sudden swift 
reaction to an act of brutahty towards yourself or another, 
or whether it is the result of being thwarted in a long- 
cherished ambition. The exultation over obtaining the 
means of satisfying a long-continued hunger is not different 
from the exultation over winning an academic honor. 
No distinction in quality can be made between emotions, 
however different may be their conditions or origin. 

Recent discussion has revolved more about the quahties 
of the emotion than the occasion upon which the quahties 



484 FUNDAMENTALS OF PSYCHOLOGY 

depend. The descriptions and explanations savor much of 
ancient theories. These had much to say about the part 
of the body that was active in the emotion and were very 
full in their descriptions of the accompanying physical 
states. Thus, Plato assigned courage, ambition, and the 
nobler emotions, to the heart; while lust and the baser 
passions had their seat below the diaphragm. In common 
observation one may find the explanation of these references 
in the sensations derived from the general region of the body 
in which the movements are felt. The changes in rate of 
breathing, in the circulation, contractions of the muscles 
of the chest and abdomen, all are noted by the chance 
observer and are prominent in the novelist's descriptions 
of mental states. While the modern author no longer 
ascribes the emotions to the internal organs in the same 
sense as did the ancients, he still looks to the organic sensa- 
tions for the coloring of the emotions ; in fact, for a quarter 
of a century, psychologists have been engaged in a contro- 
versy as to whether these organic changes do or do not 
explain both the origin and the content of emotion. 

The James-Lange Theory. — This controversy began 
with and has revolved about a theory propounded simul- 
taneously by Lange and James. The theory, stated 
briefly, is that the movements of the body, when felt, are 
the emotion; and that the mental factors are altogether 
subordinate. James states it in the apparent paradox 
that you are sad because you weep, rather than weep be- 
• cause you are sad. He enumerates a number of cases in 
which the emotion comes only after the movements have 
been felt. One may face a situation with no great appre- 
ciation of its danger, even with knowledge that it is not 
dangerous, and suddenly become aware of a trembhng, 
together with a sinking feeling in the abdomen; with this 



CHARACTERISTICS OF EMOTION 485 

movement the emotion of fear is fully established. One 
may look over a cliff with perfect confidence of safety, and 
then suddenly feel a dizziness and trembUng that destroys 
one's self-assurance and even compels one to draw back 
involuntarily. In these cases action and thought seem to 
be at variance, and action takes precedence over thought. 
The theory in general must be accepted as at least a rough 
statement of certain facts, and this makes it necessary to 
examine carefully the opposing arguments. 

Obviously the problem revolves about the possibility 
of discovering instances in which emotions disappear with 
loss of organic sensations, and instances in which the 
bodily reactions occur and give rise to emotion when the 
ordinary conditions of emotion are absent. The first 
condition was fulfilled by certain hysterical patients who 
were completely aneesthetic in both internal organs and 
external muscles. Several of these were questioned in the 
interests of the theory. The reports agree in general that 
complete anaesthesia in the parts usually involved in the 
emotions is accompanied by loss of emotion. One patient, 
a man who had always been normally emotional, suddenly 
lost all sensitivity, and immediately thereafter became 
absolutely indifferent to all that passed about him. He 
parted from his wife, of whom he was very fond, without 
any feehng of sorrow, and his reactions to experiences that 
had previously been strongly toned suddenly became 
neutral or were lacking altogether. While the fact is 
generally accepted, Sollier^ has questioned whether the 
loss of emotion is due to the disappearance of sensation 
or to the general reduction in the cortical tone in hysteria. 
Hysterical patients also suffer diminution of all the higher 
psychical functions, so that it is not at all surprising that 
^ Sollier, Le mecanisme des emotions. 



486 FUNDAMENTALS OF PSYCHOLOGY 

their ability to appreciate the experience in a way to arouse 
emotions should be lost. In this case the failure to have 
emotions would be due to the intellectual defects or to 
defects in the higher cortical centres rather than to the 
mere failure to feel responses. 

Almost as contradictory results were obtained from a 
study of actors who were questioned on the supposition 
that they would provide instances in which the emotion 
would be felt when the movements were made without any 
real occasion for the response. A number of famous actors 
and actresses were asked whether they felt the emotions 
that they depicted. The answers showed that they were 
divided into two groups: those who really felt what they 
were portraying, and a second group who merely carried 
through their parts as machines. Some asserted that they 
felt after a performance as if they had actually experienced 
the events of the play and felt during the performance as 
keenly as if the scenes were real; the others were perfectly 
cold. No definite division could be made between the groups 
on the basis of distinction or success; it seems merely that 
one group conforms to the demands of the theory, the other 
does not. James asserts that one must assume that in one 
group only the external muscles, the muscles of the face and 
those that give the bodily postures, are affected, while the 
deeper-lying reactions are lacking. It would seem from 
this that the sensations essential to the complete emotional 
experience come from the activity of the internal organs. 
The others are at least less important. 

In any discussion of this theory a sharp line must be 
drawn between the condition of an emotion and its quahties. 
James assumes the movements and raises no questions as 
to how they are excited. He takes them for granted as 
fundamental reactions of the nervous system. He is con- 



BODILY RESPONSES IN EMOTION 487 

tent in his detailed discussion to show that the emotion 
as we feel it is nothing more than the awareness of the 
bodily state; he makes no attempt to say what causes 
the reaction itself. He asks only whether anything other 
than the movements can contribute to the emotional 
experience. Granting that this in the main must be 
answered in the afSrmative, much further investigation 
remains ahead of us. 

It is to be noted in James' discussion that he does not 
specify with great accuracy what the movements in any 
particular emotion may be. He is content to assert that 
there are movements, and to prove that these constitute 
the quality of the emotion. In this most of his disciples 
have followed him. They speak much of strains, sinking 
feelings, and the Hke, but no single emotion is distinctly 
described and distinguished from others on the basis of its 
bodily accompaniments. For attempts at these details 
one must turn to recent investigations in physiology. 

Bodily Responses in Emotion 

The Sympathetic System in Emotion. — Cannon ^ and 
his students and Sherrington have made experiments 
which show what some of the changes are and what part 
they play in the emotion. Cannon asked two questions: 
I. What are the bodily responses in fear, anger, and 
general excitement? and 2. What is the value of these 
responses to the organism? For an answer to the first 
question he looked to demonstrable organic responses. 
In general, emotions were found to spread through the 
S3mipathetic system to practically all of the abdominal 
organs. Pawlow had shown that the flow of saliva and 
the secretion of the digestive fluids in the stomach were 
^ Bodily Changes in Pain, Hunger, Fear, and Rage. 



488 FUNDAMENTALS OF PSYCHOLOGY 

increased by the taste or odor of pleasant foods, even by 
sights or sounds that had been associated with such foods. 
It has also been shown that pain or the emotions excited 
in a dog by the sight of a cat or in a cat by the attempted 
attack of a dog served to check the flow of these secretions 
even when food was taken into the mouth. These emotions 
also inhibited the movements of the ahmentary canal 
which usually serve to force the food through it. Some 
of the effects may be seen in man, in whom vomiting re- 
flexes are caused at times by exceptionally strong emotions, 
particularly by sorrow and fear, not to mention the slighter 
reactions always present in disgust. 

The Adrenal Glands in Emotion. — Cannon's experiments 
prove definitely the importance of the emotion upon the 
secretions of the adrenal glands, small glands above the 
kidneys. It has been shown that this gland is called into 
activity by stimulation of the splanchnic nerve, a nerve of 
the sympathetic system. The gland was also shown to be 
excited in most of the violent emotions, by pain, anger, fear, 
and by general excitement. The effects of this secretion 
are widespread. Briefly enumerated, it serves first to con- 
tract the small blood vessels and to increase the ease with 
which the blood will clot. This action may be illustrated 
by the use made of it by the physicians in applying adrena- 
lin, the substance obtained from the adrenal glands of ani- 
mals, to stop superficial bleeding. A second action of the 
glands is to increase the amount of glycogen, or so-called 
blood sugar, in the circulation. This seems to be due to the 
action of the adrenal secretion upon the liver, causing it to 
release its stores of glycogen and pour them into the blood 
whence they are carried to the parts of the body that may 
need them. A secondary consequence of these actions is 
that the effects of fatigue are checked for a time, and the 



BODILY RESPONSES IN EMOTION 489 

muscles respond with renewed strength. This is due in 
part to the fact that the constriction of the blood vessels 
increases the blood pressure, and so more thoroughly and 
quickly washes out the poisonous products of earlier action; 
and in part to the fact that the glycogen furnishes a quickly 
assimilated food to the muscle. It could be demonstrated 
that stimulation of the adrenal glands produced each of 
these effects, the blood vessels were contracted, the blood 
pressure increased in consequence, the composition of the 
blood was changed so that it coagulated more easily, the 
liver was stimulated to secrete its sugar and, as a result, 
fatigued muscles were temporarily increased in strength. 

These same effects were all produced by pain or strong 
emotion, provided the adrenal glands were present and 
connected with the sympathetic system. The increase of 
blood pressure in emotion is well known, and experiments 
showed that the blood would coagulate more quickly after 
strong emotion. The increase in the sugar in the blood was 
demonstrated in cats subjected to pain, or which had been 
frightened by dogs when no injury could be done them. 
The same effect is exerted in man. It was found that of 
twenty-five players on a Harvard football squad twelve 
had increased secretion of glycogen, as shown by sugar in 
the urine, after the contest was over. That this condition 
was in part due to emotion was shown by the fact that five 
of the twelve were substitutes who took no part in the game 
and that the only excited spectator examined also showed 
the same reaction. Students examined before and after a 
difficult and important examination showed presence of 
glycogen after, but not before, the test. 

Looking at the phenomenon as a whole, one may readily 
see the utiHty of these reactions in emotions. The strong 
emotions, particularly the unpleasant emotions, are in 



490 FUNDAMENTALS OF PSYCHOLOGY 

animals, and were in primitive man, very likely to be fol- 
lowed by a fight or other violent effort. The animal subject 
to emotion must usually either fight or run. The bodily 
changes are a preparation for this effort. The contraction 
of the blood vessels in the abdomen forces blood into the 
peripheral vessels and the respiratory tracts, preparing 
them for greater effort at the expense of the digestive tract, 
which temporarily ceases its function. The increased glyco- 
gen and more rapid circulation under excitement supplies 
nourishment to the muscles and removes the products of 
fatigue, thus making them capable of greater activity. The 
constriction of the arteries and quicker clotting of the 
blood serve to diminish the hemorrhage in case wounds are 
received in the conflict. All together, emotion increases the 
energy of the individual and lessens the liability to injury. 
It is said in this connection that an artificially induced anger 
has been used by some individuals to spur them to greater 
effort. 

Identical Reactions for All Emotions. — Cannon con- 
cludes from his experiments that all the activities he has 
studied show the same characteristics for all vigorous emo- 
tions, whether pleasant or unpleasant, whether relatively 
passive as fear or active as anger. All this, then, must be 
regarded as having a tendency to disprove the extreme form 
of the motor theory of emotion, and even to narrow the 
appKcabihty of the statement that the characteristic 
qualities of emotion are dependent exclusively upon the 
bodily response. This theory was also seriously questioned 
by Sherrington as a result of experiments upon dogs in 
whom the connection between body and head had been 
destroyed by sectioning the upper part of the cord. After 
the operation they showed the same emotional response as 
before, had the same emotions as inferred from the reactions 



BODILY RESPONSES IN EMOTION 491 

of the muscles of the head. It was objected that associations 
may have been formed between the stimulus to the emotion 
and the expression of the muscles of the head by the inter- 
mediation of the bodily responses, and that these connec- 
tions remained after the sensations from bodily responses 
had been cut off. This objection was obviated by repeating 
the experiments on puppies only three weeks old who had 
had no chance to form this indirect association. The results 
in this case were the same as before. Sherrington is con- 
vinced that the emotion is the result of cerebral rather than 
of somatic reactions. 

Is Emotional Quality Due to Bodily Response? — If we 
accept the results of Cannon and Sherrington, it is evi- 
dently necessary to ask how much we can retain of the 
James theory. What Cannon's experiments prove is that 
there is a large background of physiological reaction and 
probably a large mass of sensations, common to emotions 
of all types. In psychological terms one can say that all 
emotion produces an excitement, and that this excitement 
has a common quality no matter what the occasion. In 
this, emotion is not unlike affection, in which it was found 
necessary to give up the old statements that the physio- 
logical responses for pleasure and pain were opposed. We 
know that both excite the same changes in circulation, secre- 
tion of tears, and of saliva. To this now we may add that 
they cause the same secretions of adrenalin and the same 
diminution of the reflexes of the alimentary canal, and that 
emotions differently aroused are also not to be distinguished 
in their fundamental physiological effects. The possibility 
remains that on top of these common elements there may 
be other responses sufficiently distinctive to constitute the 
peculiar quaUties of the different emotions. An answer to 
this question requires more detailed investigation than has 



492 FUNDAMENTALS OF PSYCHOLOGY 

been given it, for in spite of the long controversy over the 
James theory, relatively few accurate and extended obser- 
vations have been recorded of the sensations that come 
with the emotions. 

The Distinguishing Responses of the Emotions. — If 
we may attempt to supply the lack of accurate study by 
making use of chance observation, statements of novelists, 
psychologists, and acquaintances, it seems that facial ex- 
pression, the bodily posture, and a few very general feel- 
ings offer the most striking means of differentiation. There 
are characteristic differences between the facial expression 
in grief and in joy. In the one the hnes of the face are 
mostly concave downwards, in the other concave upwards. 
The bodily posture is also different, drooping and con- 
tracted in grief, erect and expansive in joy. Of the more 
internal processes the most evident seem to be an elation 
in joy and a depression with grief. One gives a Ughtness 
that seems to be localized in the chest, the other a 
heaviness with its seat in chest or abdomen. No one of 
these subjective processes has been referred to a definite 
bodily organ. Strains from the head may be added, but, 
after all, the list of bodily feelings that can be clearly 
distinguished is extremely short. Of the specific emotions 
fear may be distinguished from anger by the general weak- 
ness and relaxation of the one and the general consciousness 
of strength and the accompanying activity of the other. 
Disgust may include sensations of incipient movements of 
rejection of food either from the mouth or oesophagus. 
Wonder, to complete Shand's list of primary emotions, in- 
volves relatively slight sensations of strain from the wide 
open eyes or slightly open mouth, together with the quies- 
cence that comes from the cessation of movement. That 
these are part only of the movements or sensations involved 



BODILY RESPONSES IN EMOTION 493 

in any of the emotions considered is at once apparent. 
That the facial expression and bodily posture are not suffi- 
cient in themselves to account for the awareness of emotion 
is evident from James' evidence that an actor might act a 
part and not feel the emotion. Careful investigation may 
be able to go much farther in discovering the movements 
essential to each emotion. For the present we may content 
ourselves with the statement that on a background of 
common responses which furnished the excitement — an 
element in each emotion — other reactions occur which 
possibly are characteristic of each emotion. 

The Origin of Emotional Responses, — For the simpler 
emotions the nature of their responses can be explained at 
once as due to the original instinct. As McDougall and 
others before him put it, the emotion is merely the conscious 
side of the instinct. When one runs away the observer sees 
the running with its accompanying pallor and calls it the 
instinct of flight, while the runner has the emotion of fear. 
McDougall parallels each of his instincts with an emotion. 
Disgust accompanies repulsion; wonder, curiosity; anger, 
pugnacity; elation, self-assertion, in the same way that fear 
accompanies flight. Watson has suggested more recently 
that emotion is the innately determined response of the 
autonomic nervous system, while instinct is the innately 
determined response of the central nervous system. One 
would involve the reaction of glands and unstriped muscles, 
the other of skeletal or striped muscles. The difference 
between the two is largely as to whether emotions involve 
other than the unstriped muscles. In the main, emotions are 
marked by the internal autonomic responses. There are 
exceptions, however, which destroy the complete adequacy 
of the definition. 

On either theory the explanation of instinct in and of 



494 FUNDAMENTALS OF PSYCHOLOGY 

itself is an explanation of emotion. This holds of the larger, 
more useful responses, but many of the subtler movements 
are now merely expressive. Even these can be explained 
directly as the remnants of responses once useful to the 
preservation of the organism which in many cases have 
ceased to be useful. They arose as did all instinct by 
virtue of the survival of the organisms that developed the 
responses, or by the dying out of organisms that failed to 
develop them. A large number of the movements can be 
shown to be direct survivals of such instinctive responses. 
Running away, drawing back, or the start of fear, evidently 
removes the individual from the neighborhood of the dan- 
gerous object. Less obvious is the utility of the trembhng 
and loss of strength that come momentarily in fear. This 
may be traced to a reduced form of ' playing possum' or of 
crouching and remaining motionless as seen in the rabbit 
and other defenceless animals. It forces them to remain 
motionless and thus enables them to escape the attention 
of pursuers and possible enemies. The cry of the child is 
similarly useful in attracting attention when it is alone or is 
uncomfortable. In each of these cases, the conscious state, 
the emotion proper, is probably of slight value but seems to 
be an unavoidable accompaniment. 

General Aspects of Emotion 

Theory of Transfer of Emotional Expression. — Darwin 
has suggested that three other classes of emotional expres- 
sion must be recognized which serve still farther to explain 
or at least to classify the development of emotional re- 
sponses. These are first, that when an emotion or a condi- 
tion has given rise to one form of expression, a similar emo- 
tion or situation will give rise to a similar response. The 
second is that, granted an original response, an opposed 



GENERAL ASPECTS OF EMOTION 495 

situation will give rise to the opposite response. His third 
class is that in which certain emotions result from the direct 
overflow of nervous excitation without any controlling con- 
ditions. The first of these laws is illustrated by the sneer, 
which Darwin refers to the snarl of the dog. The dog when 
a possible enemy approaches exposes the teeth and prepares 
for an attack. In man the situation is similar and probably 
the mental attitude also. In consequence man, too, draws 
back the corners of the mouth, although there is now no 
thought of biting. Similarly, in anger, the nostrils are 
frequently slightly expanded, although there is now no 
particular utility in the movement. This Darwin would 
explain as preparation in the animal for admitting air while 
the mouth was stopped with the hairy body of the antago- 
nist. The expression continues although the original occa- 
sion no longer exists. The second class is more open to 
objection. The best illustrations are furnished by the 
movements of a cat in expressing friendliness. When angry 
the cat crouches, keeps the ears back where they will not 
be in danger of injury; the tail is down and lashing the sides. 
When pleased, the opposite of this position is taken. She 
is erect and arches the back, the tail is held high, ears erect. 
There is no particular reason for this group of responses, 
and Darwin finds it in the law of antagonism. The mechan- 
ism that leads to this opposed reaction is altogether un- 
known, and, as we have seen in connection with the feelings 
and in the recent studies of emotional expression, there is 
no evidence of a tendency to opposition in the expressions. 
The third class, of direct overflow, includes all that cannot 
be explained under the other heads. Of course it is not 
really a new head, as all are due to direct overflow of nervous 
energy, and this third class includes only such forms of 
expression as cannot be accounted for at all. Darwin's 



496 UNDAMENTALS OF PSYCHOLOGY 

instances are not very well authenticated. One was of an 
individual whose hair turned gray over night when he was 
condemned to die in the morning; the report being based 
on the statement from hearsay of a British Indian officer. 

Emotion and Language. — Certain of the emotional ac- 
companiments, in fact many of those that come from the 
more external and voluntary processes, have taken on a 
secondary value as a means of communication, as a means 
of indicating to another the state of one's mind. The facial 
expressions directly convey an impression of the emotion 
and serve as warning or encouragement to the companions 
to cease or to continue the hne of action that they happen 
to be pursuing at the moment. It is probable that the 
beginnings of articulate speech are to be found in emotional 
expression. Many of the lower animals express emotions 
through sounds, and it seems possible, even probable, that 
speech came from the association, of some general attitude 
of the individual making the sound, with the sound; and 
that little by httle other associations came to be made with 
it until our present fully developed languages made their 
appearance. We can still determine the emotional tone 
from the modulations of the voice. The loud tones and 
marked accents of anger, the dragging monotony of the 
whine of discontent, the softly modulated tones of affection 
show the emotional state very much more clearly than can 
any explicit statement in words. They can be detected 
easily in speech even in a language that we do not at all 
understand, and convey almost as much of the emotional 
attitude of the speaker in an unknown language as do words 
in our own tongue. It is not impossible that these varying 
cadences were the primary forms of expression and commu- 
nication and that the words as they developed have been 
fitted into them. 



GENERAL ASPECTS OF EMOTION 497 

Emotional Reaction to New Situations. — In the emo- 
tions of our second class, due to thwarting or furthering of 
acquired purposes, the explanation of why the movements 
should be aroused is not so direct. As was said, the bodily 
reaction, if one judge from immediate consciousness, is the 
same as in the other group. Instead, however, of having 
as the occasion for the reaction some stimulus that has an 
inherited connection with it, it is aroused by an idea or 
event that must have become associated with it through 
experience. Thus, anger or sorrow over the loss of a social 
honor cannot be said to have a definitely instinctive origin, 
but the bodily reaction may be Uttle different from that 
excited by loss of a dinner and may continue for a much 
longer time and with greater intensity. Part of this transfer 
of emotional response from immediately instinctive to 
more recently developed processes may be explained on the 
analogy of Darwin's laws. A vague similarity between the 
more complex and the simpler situation leads to the arousal 
of the same instinctive responses for both. The social honor 
is a prize which through the effect of life in the community 
has become as desirable as a bit of food. When it is lost, the 
reaction is the same as that which follows the loss of some- 
thing whose appeal is instinctive. Whatever the mechan- 
ism, certain it is that the interrelations of acquired tenden- 
cies and their interaction with the environment do lead to 
responses identical with the purely instinctive. 

One may add to these the assumption of Dewey that 
much of the quahty of emotions may be due to conflict or 
cooperation between the habitual responses. These 
acquired responses might stand to the instinctive responses 
as the acquired ideals and needs to the innate or instinctive. 
Possibly the interaction of systems of experience or of 
neurones might give rise immediately to a conscious quality. 



498 FUNDAMENTALS OF PSYCHOLOGY 

If one were to take the result of Sherrington's experiments 
at full value it would be necessary to assume some such 
effects and quahties of purely central interactions. Two 
loopholes in his argument make this conclusion doubtful. 
His experiments left his pups with a connection between 
the cortex and the facial muscles, so that the latter might 
give rise to the emotional content. Secondly, his only 
evidence of emotion was the facial expression. Really all 
that his experiments prove is that one may have the facial 
expression of an emotion without any connection between 
the cortex and the trunk or hmbs. While much work 
remains to be done toward relating particular emotions to 
bodily responses, there is every reason to beheve that the 
quaUty of the emotion, whether it be immediately instinc- 
tive in origin or arise from interrelations of purposes and 
acquired ends, is due in large part to reflex activities. Most 
of the response is common to all sorts of emotion, but added 
quahties probably give much of the distinctive tone to the 
separate emotions. 

The Kinds of Emotion. — ■ While the quality of emotion 
may be accepted as in large part determined by the bodily 
resonance, the names are not given to emotions on the 
basis of these qualities. This may be due in part to the 
large mass of sensations common to all emotions and in 
part to the fact that emotions are usually named, if named 
at all, after they have ceased to act, or by an observer. Dur- 
ing the emotion one is too much interested in other things 
to consider its quahties. In consequence names are usu- 
ally given on the criteria of the causes of the emotion or of 
its outcome. Perhaps, too, the fact that fear and anger, 
love and jealousy, and other emotions are so nearly indis- 
tinguishable is to be found partly in the fact that one 
changes into another with great rapidity. Anger is dis- 



GENERAL ASPECTS OF EMOTION 499 

tinct from fear only in the consciousness of power or weak- 
ness toward the intruding man or object, and this changes 
from moment to moment as the situation is faced. One 
first fears, then becomes angry, and again is afraid, as long 
as one is living through the experience. When the situa- 
tion is properly classified, when it is settled that one is 
stronger and must fight, or is weaker and must run, the 
emotion is said to take on a new phase, perhaps even to 
disappear. If one assume a changing response or perhaps 
a conflict of responses during the emotional state, it is no 
wonder that the physical accompaniments of opposed emo- 
tions should be identical. Both physically and mentally 
the two fuse, and one may not be sure, even after the 
event, whether fear or anger was dominant. This rapid 
alternation of expressions, taken together with the fact 
that there are always identical responses in the sjonpa- 
thetic or autonomic system, makes classification difficult 
in practice, and then largely in terms of the intellectual 
antecedents, the nature of the object, and the outcome of 
the adventure. It is this that led the popular mind and 
earlier philosophers to the classification of emotions in 
other than motor terms. 

Relation of Emotion to Other Mental Processes. — Emo- 
tions have many and close relations with the other mental 
processes. In many cases we can trace the development 
of emotions to the association of ideas. The occasion for 
the emotion is not infrequently to be found in a recalled 
event. The reaction in this case is usually not so strong 
as that made to the original event or sensation, but has 
many of its characteristic qualities. Often it seems that 
there is an association between emotional states them- 
selves. After some pleasant emotion the liability to pain- 
ful response is decreased, while after a disagreeable one, all 



Soo FUNDAMENTALS OF PSYCHOLOGY 

may tend to produce a disagreeable emotion. After one 
success has produced elation every event assumes a rose- 
ate hue, — one is easily pleased, the emotion of joy comes 
of itself. After failure, doubt assails with each new ven- 
ture. Similarly, after one fright, fear is easily aroused. In 
short, any intense emotion leaves a predisposition to the 
same or similar emotions. 

Emotion has so many similarities to feeling that it is 
difficult to draw the line between them. Almost all emo- 
tions are affectively toned. The sole exception is to be 
found in surprise. The differences between feeling and 
emotion are largely in degree. The affective tone is 
usually stronger in emotion. As the name implies, 
the motor responses are more striking and more fully 
developed. It is generally true, too, that the cause or 
occasion for the emotion is to be found on the perceptual 
level, in a stimulus as appreciated, rather than in the 
bare sensation. No one of these distinctions can be 
applied without exception, but all taken together, now 
one, now another predominating, serve to draw a distinc- 
tion in practice. 

In their relations to voluntary acts emotions have op- 
posed effects, dependent probably upon whether we con- 
sider one or the other type of emotions. In those which 
have an ideational occasion and are to be regarded as in- 
terferences with the acquired ends of the individual, the 
effect of emotion is generally to increase the motor effi- 
ciency, at least in the coarser acts. The more primitive 
emotion, the subjective accompaniment of an intense in- 
stinctive response to an external stimulus, is more likely 
to inhibit voluntary movements, particularly the more re- 
fined and accurate movements, although even here the 
actual strength is increased and the individual is probably 



GENERAL ASPECTS OF EMOTION 501 

more efiEicient in a fight or in flight. Numerous exceptions 
may be found to both rules and exceptions. Fear or even 
anger may leave one practically helpless, with a tremor or 
weakness that prevents all movement for a time and then 
probably increases the capacity. Again, shght emotion 
may enable one to carry through relatively delicate activ- 
ities, those of an artistic character, for example, that one 
might not be capable of in a calm moment. 

Emotional Control. — One may control emotions in some 
degree. The only real control is that effected at the 
source. The nature and degree of an emotion depend very 
largely upon the way a situation is classified. An event 
frequently may be referred to more than one head and 
will arouse a different emotion under each of these classi- 
fications. A human brain, presented to a class with nu- 
merous references to what the individual must have thought 
with it, and with other remarks that emphasize the per- 
sonal side, is very likely to arouse intense emotions; but, 
if considered only in connection with tracts and structure, 
may excite mere scientific interest. Many of the events of 
everyday life show the same phenomenon. Classify a re- 
mark or the man who makes a remark in one way and you 
become angry; regard it or him in another light and you 
are only mildly amused. Much also may be done by pre- 
venting expression, although this too can be controlled 
only by changing the attitude or in directing attention to 
something else until the occasion for the emotion is past. 
Either method of control becomes much more effective 
after practice. Like everything else, attitude and response 
become habitual; instinctive reactions are changed by 
habit. The physician or surgeon can look upon patients 
as cases and neglect the more personal relations. Such 
professional attitudes are taken by members of nearly all 



502 FUNDAMENTALS OF PSYCHOLOGY 

professions with the corresponding development or sup- 
pression of emotion and emotional expression. 

Possible Injuries from Control. — The control of emo- 
tion has taken on new importance with recent advances in 
the study of the causes of nervous and mental disease. 
Many of these are closely related to the emotions. Ac- 
cording to the Freudian school, all but the diseases directly 
connected with diseased tissues are to be explained as the 
result of conflicts between opposing emotions or from the 
checking of emotional expression by social pressure. Re- 
pressing an emotion has as its consequence the dissocia- 
tion of that experience from the general consciousness, and 
the repression of the experience into the unconscious which 
may result in hysteria, with its train of paralyses, anaesthe- 
sias, and other defects, or even in the insanities of the de- 
mentia precox group. The extreme advocates of the the- 
ory argue that instincts and the emotions that result from 
them should be given free rein, that any interference 
might result in a disease or in increasing the HabiKty to 
disease. Taken in the broadest sense this would be sub- 
versive of all discipline and would probably be worse for 
society than the presence of a few hysterics or even insane. 
On the other hand constant and unnecessary repression of 
all instincts, such as is seen in famihes dominated by a too 
solicitous mother or overbearing father, can be avoided 
without any serious social consequences, and may save 
the mental health of the child. The motto should be 
free vent for instincts wherever there is not too much 
injury to others, with discipHne restricted to essentials 
and exercised with as much consideration as possible. 
Where repression is necessary it should be made to take, 
as far as possible, the form of a transformation to some 
other object than that usually given it. Control by 



MENTAL STATES RELATED TO EMOTION 503 

changing the classification of the stimulus is also relatively 
harmless. 

Conclusions Concerning Emotion. — We may think of 
emotion, then, as a disturbance of the usual or normal 
course of any succession of thoughts or activities by the 
intrusion of a new or extraneous event. This event re- 
sults in a more or less prolonged disturbance of the activ- 
ities, accompanied by many useless and incoordinated re- 
sponses, and by intense affection. It is possible to distin- 
guish two types of emotion, or at least two extremes of 
emotion. One, usually the more violent but usually of 
short duration, is directly dependent upon instinct, both 
in condition and response. This is the type that may be 
defined as the mental accompaniment of an instinct. The 
second type, which is usually of slighter intensity and" 
greater duration, is conditioned by the thwarting or fur- 
thering of the system of purposes developed by the indi- 
vidual upon an instinctive basis. Even for this class the 
responses are also of instinctive origin. In this latter case, 
however, we must look to the mental antecedents rather 
than to the physical responses as the cause of the emotion, 
and as the determinant of the type of emotion that shall 
be induced by the stimulus. The bodily reverberation de- 
pends upon the antecedent mental states rather than being 
itself a first cause and constituting, through the sensations 
it excites, the entire emotion. This is not to deny impor- 
tance to the movements in giving color to emotion; it 
merely insists that other factors must be considered in dis- 
cussing its origin. 

Other Mental States Related to Emotion 

Sentiment. — Sentiment is ordinarily used to designate 
the milder, more lasting forms of emotion. Shand has 



504 FUNDAMENTALS OF PSYCHOLOGY 

varied the application of the term to indicate the antece- 
dent condition of emotions, the system of impulses that 
dominates the individual, which, when furthered or hin- 
dered, gives rise to the emotion. The sentiments are for 
him dependent upon the instincts, but the instincts are in 
turn modified and developed by experience. The two 
great systems are love and hate. These are fundamental, 
constitute the impelling forces of all activity, and give rise 
to emotion when acted upon by particular events. When 
aroused they are or may be directed toward particular per- 
sons or objects. They approach the particular emotion 
rather than the fundamental tendencies which constitute 
the impelling force needed for the development of emo- 
tion. This definition emphasizes the characteristic of du- 
ration implied in the usual meaning of the word, and has 
been accepted by McDougall and Stout. There is no 
doubt that a name is needed which shall designate the 
systems of impulses or purposes. However, some word 
implying greater force would be better than sentiment, 
since these systems are the forces behind all voluntary ac- 
tivities, mental and physical, as well as the occasions for 
the emotions. What is designated is more like what is usu- 
ally called desire or a system of desires than sentiment. 
While the authority behind this definition of the word en- 
titles it to respect, sentiment seems better suited to desig- 
nate the mild continued emotion, its more usual meaning. 

Mood and Passion. — Mood is a predisposition to an 
emotion of comparatively short duration. It may be due 
to physical causes. Lack of sleep, a fit of indigestion, and 
many other indispositions predispose to unpleasant emo- 
tions, while good health and rest conduce to pleasant emo- 
tions or sentiments. Moods, too, develop from earlier 
emotions. A disagreeable emotion, as was said above, 



MENTAL STATES RELATED TO EMOTION 505 

leaves a tendency to other unpleasant emotions, and this 
is a mood. Moods, then, are rather dispositions to emo- 
tions than any particular kind of consciousness or behavior 
of themselves. Passion, like sentiment, has been used in 
various ways at different times and by different men, now 
being extended to cover the entire field of pleasant and un- 
pleasant acts or mental states, and again restricted to the 
more violent exhibitions of the emotional reaction. At 
present it can hardly be said to have any technical mean- 
ing. As in the popular sense, it most frequently designates 
the more violent forms of emotion. 

Temperament. — Temperament is a word with a long 
pedigree in psychological usage and one that has under- 
gone little change in application since first introduced. 
Galen recognized four humors in the body, blood, phlegm, 
black bile, and yellow bile, and assumed that the disposi- 
tion of the individual was largely determined by the one 
that was dominant. These gave rise respectively to four 
principal temperaments, the sanguine, the phlegmatic, the 
melancholic, and the choleric. These names still persist, 
although they have taken on slightly different forms at the 
hands of different psychologists and in the popular mind. 
Thus Wundt makes the temperaments depend upon com- 
binations of rate and strength of response in a given indi- 
vidual. The sanguine is said to be quick and weak, the 
choleric, quick and strong, the melancholic, slow and strong, 
the phlegmatic, slow and weak. This corresponds to cer- 
tain of the characteristics of the terms as popularly used, 
but omits what seems the most important, the tendency to 
pleasant or to unpleasant emotions. On the whole, the 
schematism of Wundt has little to recommend it over the 
looser applications of the term in popular speech. All to- 
gether it can hardly be said that we know more about tem- 



5o6 FUNDAMENTALS OF PSYCHOLOGY 

peraments than that individuals differ in their susceptibiHty 
to the different emotions. At present there is no com- 
plete classification of these dispositions. The ideal of Ga- 
len, that one might group individuals in such a Vv^ay that it 
would be possible to determine what mental and physical 
capacities and dispositions were necessarily associated and 
find some simple test that would determine to which of 
these classes each individual belonged, is almost as remote 
to-day as it was when Galen wrote. 

The Ductless Glands in Relation to Mood and Tem- 
perament. — A very suggestive recent theory would relate 
temperament and mood to the dominant action of various 
glands of internal secretion, the endocrine or ductless 
glands. We have seen that the adrenal glands are sup- 
posed to be an effective factor in the excitation of the emo- 
tions. The other ductless glands may by their secretions 
prepare the way for emotional outbursts or for the re- 
straint of the emotions. Those most frequently men- 
tioned are the thyroids, the pituitary, and on less definite 
evidence the thymus. It is assured, for example, that ex- 
cess of thyroid secretion, as in Graves' disease, renders the 
subject much more excitable and more responsive to both 
pleasant and unpleasant emotions. Lack of the normal 
amount of secretion decreases intelligence. The posterior 
part of the pituitary body, a gland on the anterior side of 
the mid-brain, secretes a fluid into the blood which has a 
tendency to increase contraction of the involuntary mus- 
cles. Less well based is the suggestion that the thymus if 
active for too long in the life of the individual induces the 
persistence of a childish disposition. The various secre- 
tions act through the blood either on the nervous or mus- 
cular tissue to produce these effects. This modern theory 
would replace Galen's humors by the names of these duct- 



MENTAL STATES RELATED TO EMOTION 507 

less glands. If accepted we would have the thyroid tem- 
perament, the pituitary temperament, the thymus tem- 
perament, etc. It is undoubtedly an advance on Galen, 
and promises much for the future. 

REFERENCES 

James: Principles of Psychology, Vol. II, Ch. XXV. 

Shand: Foundations of Character. 

Darwin: Expression of Emotions in Animal and Man. 

Ribot: Psychology of Emotions. 

Jastrow: Temperament and Character. 

Watson: Psychology from the Standpoint of a Behaviorist, 

Ch. VII. 
Berman: The Glands Regulating PersonaUty. 



CHAPTER XVII 

THE GENERAL PRINCIPLES OF ACTION 
AND THE WILL 

Action 

The final outcome of all thought, of all mentai processes 
whatsoever, is action. In connection with the nervous 
system it was seen that all stimulations tend to find an 
outlet through the motor nerves and muscles. Movements 
play an important part in almost all mental states. Move- 
ments accompany all acts of attending, and several authori- 
ties explain the fact of attention itself by the movements 
called out, rather than by the antecedent mental states. 
In perception, movements are used as a means of explain- 
ing space, time, and rhythm; recognition is, for some 
authorities, merely a revival of old movements. We find 
many writers who explain many if not all of the essentials 
of the reasoning processes in terms of movement. Either 
as beginning, intermediate stage, or end, of every mental 
state, we find that action has an important place in fact 
or theory. 

We may assume in our present chapter that action is 
the real aim of life, and that most of the operations so far 
discussed are prehminary to it. This action may follow 
immediately upon them, or may be delayed for a consider- 
able period. Here, however, we are more concerned to 
see how the other processes lead to action, than to under- 
stand how the movements may explain them. In the first 

place, we may assert with some confidence, on the basis 

508 



ACTION 509 

of practically universal agreement of psychologists of to- 
day, that there are no new forces, nor even any absolutely 
new laws involved in the control of action. All mental 
states give rise to movements of greater or less extent; 
and, on the other hand, movement as a psychological process 
can be explained only in terms of certain mental states 
already discussed. Were we to give a complete explanation 
of movement, we should have a review of each of the pre- 
ceding chapters, with an appendix on the way in which 
movement resulted from the process discussed in it. We 
can at most add the appendix matter in this chapter. 
Assuming that the fundamental principle of action is that 
all excitations tend to pass over from the sensory to the 
motor neurones, we may raise several fundamental questions 
in connection with this process which may be discussed 
or put aside now before we proceed to the details. 

Sensation and Movement. — One of the most important 
is whether the sensory excitation that leads to movement 
must be accompanied by sensation. The evident answer 
is that sensation may or may not accompany the process. 
Some assert that normally all movement comes from 
sensation, but we have also the opposite view that all 
sensation is aroused by the excitation of the motor neurone 
or even by the movement itself. Neither of these extreme 
views need concern us here. We may be content with the 
statement that the excitation of motor processes certainly 
often takes place with no accompanying sensation, and 
that all that is really necessary for the movement is 
the previous excitation of some sensory organ or sensory 
neurone. This latter may come through some indirect 
path involving a memory, or the cortical cells ordinarily 
active in memory. The natural thing is for the sensory 
process to discharge into movement. What really needs 



5IO FUNDAMENTALS OF PSYCHOLOGY 

explanation is why at times the sensory excitations do not 
cause movements. In the complete sense they probably 
never fail to arouse some response, but it is frequently too 
slight to be noticed. The fundamental fact of action in 
general needs no special explanation. 

Learning 

The Methods of Learning. — Starting with the single 
assumption that movements always follow upon, and are 




Fig. 94. — Animal problem box. (From Thorndike, "Animal Intelligence.") 



the outcome of sensory stimulations, the first question 
that confronts us is the discovery of what it is that de- 
termines the particular movement which shall follow upon 
any given stimulation. We have seen that certain con- 
nections are present in the organism at birth, the result of 
the heredity and evolution of the individual and of the 
species, and that learning by trial and error controlled by 



LEARNING 511 

instinct supplies the remainder. We may here give a 
more detailed account of the process of learning. 

The experiments upon animals were begun by Thorndike, 
who tested the methods by which a cat learned to escape 
from a box that had a door fastened by a simple catch, a 
button that could be turned, or a bolt that might be drawn 
by pulling a string hanging down inside the box. To 
make sure that the cat would make an effort, it was hungry 
when put into the box, and food was in sight on the outside. 

IThe process of learning has been found to depend in 
practically all animals upon the presence of random 
movements, — is one of trial and error. The cat 
makes a large number of movements of all sorts, tries 
to force herself through all promising openings, bites 
at all projections, scratches, and mews; in fact, she 
exhausts all the acts, reflex, instinctive, and habitual, 
that she has at her command. Sooner or 
later one presents itself that happens to 

open the 
door. She 

". ~ ' I I ' scratches at 

the button 

Fig. 95. — Curve of learning in dogs. Height shows time required 

for hitting upon each correct response. (From Thorndike.) and Dypure 

chance 
turns it. When the door is open she walks out. But one 
successful movement does not teach her the method of 
opening the door. When put in again, she goes through a 
series of random movements a second time, and again will 
hit upon the correct response by chance. It is only after 
a number of successes — the number varies with the in- 
telligence of the animal — that the right movement will 
be begun at once when the animal is put into the box. 
Each trial will, on the average, require less time than the 




512 FUNDAMENTALS OF PSYCHOLOGY 

one that preceded it, but there are many variations owing 
to chance difficulties. 

This process of learning by trial and error governs all 
of the learning of animals so far experimented upon from 
the very lowest to man. How low in the scale we may go 
depends upon what is meant by learning. In the early 
chapters it was noted that Jennings found that movements 
were modified by the results of earher actions even in the 
unicellular organisms. The Stentor, for example, would, 
when slightly stimulated, at first bend to one side and then 
later give up all responses. If the stimuli were made 
more intense, it would first bend away sharply, and then, 
after several responses which failed to remove it from the 
excitation, would release its hold and swim away. This, 
the most rudimentary form of learning, is nevertheless 
learning. From that point on, more and more complex 
movements may be acquired as the organism increases 
in complexity. The essentials of the learning process in 
animals seem to be that any problem must be solved 
by chance at first; that, after the right movements have 
been hit upon a sufficient number of times, a connection 
is established between a certain stimulus or group of stimuli 
and the movement, in such a way that the stimulus tends 
at once to call out the corresponding movement. 

The Nervous Basis of Learning. — This still leaves open 
the question as to what brought the so-called chance re- 
sponse in the first place. If we turn back to the nervous 
system, it may be said that a given sensory impression 
stimulates a sensory neurone, which in its turn has axones 
connected with a number of motor neurones. The synapse 
to one of the motor neurones probably offers least resistance 
and the impulse passes across that. If the result which 
comes from the act gives pain or does not remove the 



LEARNING 513 

unpleasant stimulus, a new set of responses will be started 
as the stimulus becomes strong enough to open less per- 
meable synapses. If, for example, the cat does not escape, 
get the meat, and in consequence begin the instinctive 
responses involved in eating, then new synapses will be 
opened and other movements result until some change 
in the stimulation starts a new series of responses. It 
should be remembered that there is not one stimulus but 
many, and that, as attention changes, new stimuli come 
which also make possible new movements. When the 
movement has been made, the same stimulus will produce 
the same movement, and each repetition reduces the re- 
sistance at the synapse as in the formation of association. 
In animals and in the ordinary learning of man, each move- 
ment is the result of instinctive responses or of earlier 
habits. Watson asserts that there is no real formation of 
new connections in learning, but that all is due to the 
elimination of certain of the unnecessary movements in 
the first trials. His theory is that the inherited connec- 
tions usually offer roundabout paths between stimulus and 
movement. This series of responses is innate. Trial and 
error finally make a more direct connection between the 
stimulus and the successful act. On this theory learning 
could never lead to absolutely new connections. It could 
only shorten the course. Undoubtedly a large part of 
learning is of this character. 

To What Extent are New Connections Formed in Learn- 
ing? — In man, however, there seem to be cases in which 
there is no natural nervous connection at the synapses, 
or at least in which the instinctive connection is very weak, 
and in which learning takes place through a spread of 
impulses over synapses very sHghtly permeable. Thus, 
in learning to move the ears in the experiments that Bair 



514 FUNDAMENTALS OF PSYCHOLOGY 

carried out, a connection was formed, a path of discharge 
was opened to a muscle not ordinarily under voluntary 
control. Here there seemed to be a gradual spread of 
impulse from the usual channels to more and more unusual 
ones, until finally it chanced to find the old path to the 
retrahens muscle, the muscle that pulls the ear back. 
Then repetition stamped in the connection until it could 
be repeated at will. Another case of the formation of new 
connections is furnished by the surgical operation that 
replaces an impaired nerve by another with an altogether 
different central connection. Thus, when there has been 
paralysis of the nerve innervating the flexor muscle of the 
arm, it has been possible to divide the nerve supplying 
the extensor muscle and connect one part of it with the 
injured flexor muscle. When it has regenerated, the nerves 
that previously produced extension of the arm now carry 
the impulses which produce flexion. Here evidently we 
cannot be dealing with a dropping out of old connections 
but must have the formation of altogether new ones. Even 
more convincing are the experiments and treatments of 
Lasher and Franz. They showed that a monkey which 
had had an arm paralyzed by extirpation of the controlling 
area in the cortex would completely recover the use of the 
arm if forced to use it, although there was no regeneration 
of tissue. Constant trial induced similar recovery of func- 
tion in men in cases of long-standing paralysis due to disease. 
These paralyses must be overcome by the opening of new 
connections between sensory and motor neurones by the 
process of trial and error. All three instances involve 
formation of connections that are not definitely present at 
birth; in the second instance, in fact, they follow paths 
and produce movements the reverse of those that are in- 
nate. Indeed, much evidence is accumulating that there 



LEARNING 515 

is considerable variation in the paths followed during the 
same function of the cortex. If confirmed, this fact would 
prove that the formation of new connections is the rule 
rather than the exception. 

The Acquisition of Skill. — In the adult man the most 
important practical problem of learning is how series of 
acts, already under control in isolation, may be united 
into a single series, and made to constitute a unitary group. 
This is what happens when one acquires skill in any game 
or occupation. A number of investigations have been 
carried out on problems of this sort. Bryan and Harter ^ 
investigated the learning of the telegraphic language; 
Swift studied typewriting, tossing balls, and learning 
Russian; Bair and Book investigated typewriting. All 
obtained the same general result, that skill comes rapidly 
at first and then more slowly, and that in the course of the 
work there are many periods in which no progress is made, 
followed by periods of rapid improvement. In each of 
these tasks the individual movements are known in advance. 
One can press the key of a telegraph instrument or of the 
typewriter or toss a ball at the start. What is necessary 
is to organize the whole so that one element shall start the 
next, and all shall be carried on together without false 
movements, and as rapidly as is possible. All agree that 
improvement here, like the original learning, comes largely 
by chance successes. One hits upon some more effective 
combination of movements without any definite foresight, 
and even without knowing what it was that caused the 
improvement. The worker does his best all along, and at 

1 Bryan and Harter, Studies on the Telegraphic Language, Psychological 
Review, 1897, p. 27. 

Swift, Acquisition of Skill in Typewriting, Psychological Bulletin, 
Vol. I, p. 295. 



5i6 FUNDAMENTALS OF PSYCHOLOGY 

times an improvement comes, at times it does not. There 
is always fluctuation from day to day. This seems due in 



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5 10 15 20 25 30 35 40 45 50 



Fig. 96. — Curve of learning to write on the typewriter. The horizontal distances 
show the number of days of practice; the vertical, the number of words written in 
an hour. Curve i shows the progress during the original practice; curve 2, the re- 
sults of nine days' practice after an interval of two years and thirty-five days. 
(From Swift.) 

part to the general physical condition, in part to chance 
changes in the character of the work. The preliminary 



LEARNING 517 

feeling offers little or no indication of what the course of the 
work is to be. One may feel well, even feel certain that a 
good score is to be made on a certain day, and find that 
the accomplishment is lower than on days when the general 
feeling seems to offer less hope of success. 

Plateaus in Learning. — One of the most interesting 
questions is why there should be the long periods of no 
progress, the so-called plateaus. They have been reported 
by all observers and are present in most of the curves. 
The same amount of effort is made, and all the conditions 
seem to be approximately the same, but no progress results 
for a long interval. Various explanations are given for 
them. Bryan and Harter assert that they are periods in 
which the old associations or partial habits are being more 
firmly implanted, and that this is essential for any farther 
advance. In certain cases this seems true. It has also 
been asserted that they are periods in which the worker 
loses interest and relaxes effort, but most workers do not 
accept this as a general explanation. They are also found 
when effort is kept at a maximum. Assuming that the 
plateaus are necessary as preparation for a new advance, 
the reason for the rise to a new level offers difiiculties. 
Three explanations have been suggested, (i) The simplest 
is that the preparation has been completed and then some 
new combination of movements is hit upon that makes 
the progress possible. (2) Even Bryan, who argues that a 
plateau is a period of preparation for increased efficiency, 
insists that there is often at least some special stimulus. 
He quotes instances of telegraphers who have spent some 
time in a small office who show a sudden rise in ability when 
transferred to a main line office. Here increase is probably 
the result of new incentives. (3) A third important factor 
lies in becoming clearly aware of the conditions of the prob- 



5i8 FUNDAMENTALS OF PSYCHOLOGY 

lem, of what must be done to gain full control, — with this 
there is frequently an increase of skill. Effort may be 
helpful, or may not, according to the time at which it is 
exerted. If all is ready, increased effort may give increased 
effectiveness; if the effort comes too soon, it may be a 
detriment and even lead to postponement of the advance. 
Batson^ carried out an investigation of the learning pro- 
cess for tossing balls. His conclusion is that the plateaus 
are the expression of the time taken to associate several 
movements into a chain, when the separate movements 
must be combined into a unit before new progress is possi- 
ble. Thus, keeping two balls in the air with one hand 
requires three separate acts, estimation of direction, esti- 
mation of the right height to throw the balls or of the force, 
and estimation of the time required for the balls to rise and 
fall, since the ball is seen only at its highest point. Unless 
these three acts could be made together, no real progress 
was possible. The plateaus were thought to correspond to 
the periods during which the three factors were being com- 
bined, or during which each was being learned separately 
before they could be combined. If the act to be learned was 
simple, involving only one process, no plateaus were found. 
If attention was distributed over the entire process, if all 
three part processes were attended to at all times, the 
plateaus were not so likely to appear. In Batson's experi- 
ments they were found only in composite acts where the 
parts were attended to separately and then joined into 
groups. Whether this explanation will hold for all problems 
can be determined only when others have been analyzed 
into their parts in a similar way. We may content our- 
selves here with the statement that acquiring skill in com- 

1 Batson, Acquisition of Skill. Monograph Supplement, Psychological 
Review, Vol. XXI, 1916. 



LEARNING 519 

plex acts is, like learning in the simpler forms, due to 
chance trial and error, a process in which the learner does 
not know how he makes advances either before or after they 
are made. The associations are formed through frequent 
repetition, and the plateaus, or stages of no progress, are 
periods when associations necessary to new progress are 
being formed. The rise comes through some new acciden- 
tal combination, due to some new incentive, to an under- 
standing of the conditions of the advance, or merely to the 
perfection of preliminary connections essential to making 
new combinations possible. 

Learning by Imitation. — A suggestion that may 
deserve a moment's notice is that one may learn by imita- 
tion. In one sense this is of course very largely true. We 
tend to imitate the more striking acts of those in whom we 
are interested and with whom we come into contact. But 
at most this acts as a goal toward which one may strive by 
a process of trial and error, rather than as an immediate 
cause of the action. That there is no fundamental impulse 
to imitate is evident from experiments made with animals. 
Thorndike found that when one cat was permitted to watch 
another get out of a cage a number of times, the time it 
required to make the same movements was not noticeably 
shortened. Similar results have been obtained by various 
other investigators under approximately the same condi- 
tions. In his work, referred to above, Bair found that even 
compelling the muscle to make the movement to be learned 
by stimulating it by an induction current did not decrease 
the time required. The impulse must develop from the 
cue or stimulus ordinarily used to incite the movement, if 
learning is to take place. External aid serves at most to 
direct attention to the right movement; but to make it, 
if it be not already learned, requires the usual process of 



520 FUNDAMENTALS OF PSYCHOLOGY 

trial and error. The same statement may be made of the 
effect of imitation in more complex acts that are already at 
command. The sight- of another making them serves to 
give the idea, and that may, if desired, lead to the act. 
What force it has is due to the general social instincts, rather 
than to any specific instinct or impulse to imitate. 

Movement 

Consciousness and Movement. — When one attempts 
to determine the factors that precede and control move- 
ments already learned, to ask why the movement is made 
and how it is controlled, one comes upon rather more 
difference of opinion. We have already seen that all move- 
ment follows upon stimulation. These stimulations can 
be traced in the last analysis to sensory excitation. In 
most of the more elaborate acts of human adults, some 
consciousness accompanies this excitation, and in a very 
large number of cases the excitation that precedes is from 
the activity of a memory tract rather than from the stimu- 
lation of a sense organ directly. Each of these factors 
introduces certain complications and raises questions that 
must be discussed. One of the first is, what does conscious- 
ness add to the process and is it necessary that consciousness 
should be present? Here opinions differ. Consciousness 
does accompany many if not most acts when they are first 
made. On the other hand, before an act has been definitely 
learned, consciousness of what is to be done seems, as has 
been said, to help very little in the learning; after it has 
been learned, consciousness becomes more and more indefi- 
nite until finally it may completely disappear. In view 
of these facts it seems difficult to do more than insist on 
the importance of the sensory innervation as universally 
present. The degree of consciousness and what its effect 



MOVEMENT 521 

upon movement is, may be left an open question; and its 
presence need be pointed out only where what is conscious 
gives a definite explanation of the characteristics of the act. 
Initiation of a Movement. — We may divide the conscious 
accompaniments of movements into three groups. First, 
the initiating processes; secondly, the directing sensory 
processes; third, the awareness of the result. These must 
be considered separately. What the initiating process may 
be has been much discussed, and many suggestions have 
been made concerning it. Probably all have been too 
definite. Thus, several have inchned to the view that 
movement must be preceded by the kinassthetic sensation 
that arises when the movement is made. To speak a word, 
one must recall the sensations made when that word has 
been uttered at some earher time; or to move the hand to 
cut the leaf of a book one is reading, one must recall the 
sensations felt when that movement was made. Woodworth^ 
has shown that these sensations are seldom present, and a 
little observation will indicate that you do not ordinarily 
have them in mind before the movement is made. Visual 
images are more frequently present, but even these are not 
always definite. If you decide to rise and walk across the 
room, you will see that all that is necessary is to notice a 
book and remember that you must read something in it 
before you go on. With a very general idea and the sight 
of the book, the movement begins and is carried to its con- 
clusion. Even visual images are not always present. This 
is too obvious to mention in the case of speech, which is 
influenced more by auditory images. In most cases the 
imagery that precedes, whose presence may be regarded 
as constituting the intention to move, is very schematic; 

' Woodworth: The Cause of a Voluntary Movement. Carman Volume, 
P-35I- 



522 FUNDAMENTALS OF PSYCHOLOGY 

and almost anything in any way related to the act may serve 
as the incentive to movement. 

Meaning as an Incentive. — In this, action is very little 
different from thought. In fact, Woodworth first came to 
his hypothesis of imageless thought through a study of the 
mental content that precedes action. As in thinking, our 
memories and ideas are brought into systematic groups, 
in which any one element may serve to represent any other, 
so the antecedents of acts are also grouped, and the act 
results from the appearance of any element of the system. 
Organization is as evident in the control of action as in the 
control of thought. Just as an idea which is not at all simi- 
lar to an object may represent that object, so an idea or 
sensation that has been only indirectly associated with a 
movement may come to represent that movement and in 
fact constitute the intention to make it. In practice one 
finds that almost any idea or impression that has been 
connected with an act may be the immediate predecessor 
of that act. Any mental process may constitute the incen- 
tive to any act with which it has been closely associated, 
in the same way that any image may have as its meaning 
any idea with which it has been associated. Colloquial 
language connects the two, and uses the single word for 
both. ' I mean to do that ' is a common expression as the 
equivalent of 'I intend to do that,' and the use of the term 
is justified by psychological analysis. A meaning, using 
the term in the technical sense of the earlier chapters, may 
quite as naturally have an issue in movement as stop short 
in the mere representation of an idea. 

Different Types of Antecedents of Movements. — Three 
distinct classes of mental processes may be discovered 
among the antecedents of action, (i) The most common 
is the intention or the meaning, a representation in some 



MOVEMENT 523 

form of the goal or result of the act. This goal may be 
represented as a concrete sensation, as a very general 
notion, or may have no appreciable imagery, or at least no 
appreciated imagery. It may take any of the forms of a 
concept. The initiating idea for a stroke at golf may be a 
definite image of the point where the ball is to land, it may 
be some vague verbal thought that it is well to land near 
the tree on this hole, or it may be that the stroke is guided 
by nothing more definite than the assumption that the 
next stroke is in that general direction, an assumption that 
is not formulated but is due to the appreciation of a particu- 
lar step in the game. It must be said that this stage is very 
rare in a game of skill, but much more frequent in partially 
automatized tasks. (2) At times, intention is lacking or 
much in the background, and a sensation or idea closely 
associated with the movement serves as the incentive. 
This may be either the kinassthetic image mentioned above, 
or it may be the sight of an object, as when a spot on the 
tablecloth catches the eye, and the finger moves towards 
it even to the later embarrassment of guest and hostess. 
The second cue is different from the first in that it does not 
correspond to a purpose, or may be directly opposed to the 
general purpose. (3) Finally, some sensory stimulus may 
cause a movement that is altogether unrelated to the inten- 
tion of the moment. 

Interaction of Incentives. — These three different sorts of 
antecedents may oppose and disturb each other in the con- 
trol of the resulting movement. The intention is the most 
frequent antecedent but, if at any point in carrying out 
the intention an extraneous idea be permitted to become 
dominant in consciousness, it disturbs or prevents the move- 
ment. Thus, if one is making a golf stroke and suddenly 
permits the ditch immediately in front to catch attention, 



524 FUNDAMENTALS OF PSYCHOLOGY 

the ball goes into the ditch in spite of the good general 
intentions of the player. In a baseball game, in the same 
way, if some object other than the point at which the ball 
should be thrown is attended to, a bad play is fairly certain 
to result. Even the attachment of a not to an idea does 
not always prevent it from affecting the act. Langfeld ^ 
found that in experiments which consisted in moving a 
wire along a groove, endeavoring to avoid touching the 
sides, the experimenters were more likely to touch the edge 
if he asked them not to touch it than if he told them to keep 
the wire in the middle of the groove. Attention to the side 
induced a movement toward it in spite of the intention to 
avoid it. Within limits, trying not to do a thing has the 
same effect as trying to do it. This is particularly true in 
acts of skill and of movements only partly learned. It is 
true in general that an intention of the more remote sort 
is frequently conquered by an idea of a specific movement, 
even if that be directly contrary to the intention. The same 
holds of the third type of antecedent, a sensation not 
directly connected with the movem_ent. A sudden stimulus 
that comes in the course of an attempt to make a difficult 
movement will frequently disturb or destroy it. A sudden 
loud noise or bright light spoils a delicate line with the pen, 
or the aim of a rifle, or a drive at golf. Not the meaning 
alone, but that, together with the idea or object that holds 
attention, or the sensory stimulus that forces its way into 
consciousness, serves to direct the movement. 

The Control of Movements. — The sensations aroused 
by the movement constitute the second of the three groups 
of conscious states accompanying movement. These sen- 
sations serve primarily to direct the act. Movement is 

1 Langfeld, Movement under Positive and Negative Suggestion. Psy- 
chological Review, Vol. 20, p. 459. 



MOVEMENT 525 

in this respect much like memory or reasoning or the process 
of learning. The incentive must be distinguished from the 
control; the attempt, from the recognition of success or 
failure, together with the correction that goes with the 
latter. In addition to the sensory processes that initiate 
the movement, the accompanying sensations exercise a 
constant guidance. These are divided by James into two 
classes, the resident and remote sensations. The resident 
are the kinaesthetic sensations. The remote are the sensa- 
tions from eye or ear, that indicate where the moving mem- 
ber is, or what the sound is that is being produced. Both 
of these sensations or groups of sensations ordinarily control 
the movement without being directly noticed. As a finger 
is moved with the eyes closed, the kinaesthetic sensations 
are constantly coming to the cortex and sending out reflexes 
which serve properly to direct the movement and to adjust 
its force and extent. They are most easily demonstrated 
by their absence. In tabes the motor nerves are unimpaired, 
but the posterior columns in the cord which carry the kinaes- 
thetic sensations are destroyed. A characteristic symptom 
of the disease is inabihty to control movements. When the 
eyes are closed, the patient is not able to bring thumb and 
finger together accurately and still less to bring two fingers 
together in front of the face with a single sweep. Locomotor 
ataxia with its irregular gait is one form of the disease. 

Remote Sensations. — The remote sensations are also 
active in detecting and correcting any departures from the 
intended course of action. Thus, when writing, if the hand 
starts to make a crooked fine, the deviation is at once seen, 
and the eye directs the pen back to the right path. The 
influence of the eye is not appreciated; but, if one attempts 
to write with the eyes closed, it is at once apparent that an 
important correcting force is lacking. The ear acts in the 



526 FUNDAMENTALS OF PSYCHOLOGY 

same way in governing speech and the tone in singing. Ex- 
periments show that most singers, some of them among the 
most famous, are not able to strike the correct tone at once, 
but make an attempt, are quick to detect that the tone is 
too high or too low, and so adjust the pitch to the correct 
one. The viohnist, too, does not estimate the position of 
his fingers on the string by the kinassthetic sensations, an 
estimation that would require marvellous accuracy, but 
approximates the position first, and then, as the bow begins 
to give the tone, he adjusts the length of the string until 
his ear tells him that the tone is correct. That the remote 
sensation is essential is shown by the fact that the deaf 
cannot speak without special training. The training con- 
sists in teaching the patient to control the voice by kinaes- 
thetic and tactual sensations instead of by the sounds that 
are used by the individual who hears. The deaf child 
feels the teacher's vocal organs, and keeps trjdng until he 
makes his own carry out the same movements. The same- 
ness of movement is at first recognized by touch, but with 
practice the kinsesthetic sensations from the vocal organs 
sufhce. These control processes also become automatic, so 
that one notices neither the sensations themselves nor the 
fact that they exercise control. The sensations from the 
eye guide the hand reflexively, or with as Httle thought as 
is required for the reflex. 

Another striking case of reflex guidance of this sort is 
that exerted by the static sense, the stimuli from the 
vestibular branch of the auditory nerve. This, as was seen 
in the earher chapters, makes close connections with the 
motor centres in the brain stem, particularly with the 
cerebellum and the roots of the motor ocuU nerves. These 
sensory nerves probably give no sensations, but nevertheless 
they guide the movements of the body as a whole, serve to 



MOVEMENT 527 

keep the balance, give rise to compensatory eye movements, 
— movements that keep the eyes fixed on the same point 
in spite of the movements of the head and body. The 
sensory impulse calls out these movements continuously 
and often we have no knowledge that the movement has 
been made; certainly we have no appreciation of the fact 
that they produce the movements. The stream of im- 
pulses coming in through the vestibular nerves constitutes 
one of the important forces which control any movement 
of the trunk. 

Any act, then, may be said to be the outcome of the appre- 
ciation of a situation that requires movement. The imme- 
diate incentive is usually some object or idea that for the 
moment holds the centre of attention. But this incentive 
is seldom the picture of the movement to be made; more 
frequently it is some idea of the end to be accompKshed. 
If the movement is relatively unfamiUar, it is an idea of some 
immediate act; if very familiar, a more remote end is usu- 
ally held in mind. The intention does no more than mean 
the movement; it seldom recalls it in sensory terms. The 
movement is always guided by the resident and remote 
sensations. These adjust it to the conditions of the moment. 
When a movement has been repeated sufficiently often to 
become automatic, attention is needed only at the be- 
ginning. The act is started, and attention then turns to 
something else ; the association between the movements and 
the resident and remote sensations serves to carry it to its 
goal. Thus, in walking on a famihar course, one merely 
decides to go to a certain place and, when once started, one 
step starts the next, always under the control of the remote 
and resident sensations. The visual stimuli lead to the 
avoidance of obstacles and guide in making the necessary 
turns. Unless some new obstacle is encountered, one may 



528 FUNDAMENTALS OF PSYCHOLOGY 

go into a ' brown study ' at the moment of starting and not 
realize again what is going on about until the destination 
has been reached. All movements or chains of movements, 
at first learned or joined together by effort and under the 
influence of a complete consciousness, tend gradually to 
lose more and more of the conscious accompaniments and 
antecedents. Finally, in more complex acts, they may start 
from some unnoticed stimulus; in the case of simple acts 
or a number of unified simple movements, they may be 
started by a single idea, may be initiated by a conscious 
process and guided to their end by habit without further 
consciousness. Associations between the movements them- 
selves or between the resident sensations of one movement 
and the motor processes required for the next, take the 
place of all more definite awareness. Even in these auto- 
matic acts, there is guidance by a wide group of habitual 
connections between neurones, not at all appreciated by 
the agent. 

Choice 

Choice and Motives. — We have been assuming, all 
through, that the intention to make a movement has been 
present, but a process antecedent to the intention requires 
discussion. This is the problem of choice. It is true that 
most acts are automatic or habitual, that the decision was 
determined long before the time of performing the act, 
and, when the occasion presents itself, is carried out im- 
mediately. But in some instances two opposed acts are 
felt to be possible, and it is necessary to choose which is to 
be made. The actual act of choice is relatively simple. It 
amounts merely to giving one intention free play and 
checking the others. The actual mental content consists 
in attending to the movement to be made or the result to 
be attained. When the choice or decision is made long be- 



CHOICE 529 

fore it is to be carried into effect, it consists frequently in 
outlining the course of action in words or in some idea, — 
some concept perhaps. When the time comes, the stimuli 
present lead at once to the act. The only new problem 
in connection with choice is as to what leads to the inten- 
tion, why one course is chosen rather than another. This 
depends upon the selection of one or the other of the possible 
ends present to consciousness. The explanation lies finally 
in the laws of attention and association, and offers little 
that is new. The deciding factors are the subjective con- 
ditions of attention and of association. One seldom re- 
gards as choice the decision determined by objective fac- 
tors alone. 

Mental Attitude in Control of Choice. — The influence 
of the situation and the mental setting or context have 
been frequently mentioned above. It was brought out in 
a slightly different form by Ach^ in a long investigation 
of the conditions of choice by means of the reaction experi- 
ment. First he asked his subjects to move the right finger 
when a letter E was shown, and the left when the letter 
came. The times required for making each movement were 
measured. It was found that no real decision was made 
after the cards were shown, but that the movements were 
made at once because of the previous preparation. This is 
evident from the fact that more time was required when 
the subject was left free to react with either finger than 
when the finger to be moved was prescribed. In the latter 
case part of the preparation for action had been completed 
before the movement began. These facts may be regarded 
as indicating that the first form of reaction gives play to 
choice, while the others are determined by the conditions 
of the experiment, the purpose of the moment. It was in 
^ Ach, Ueber die Willenstatigkeit und das Denken. 



530 FUNDAMENTALS OF PSYCHOLOGY 

these same experiments that the control of the arithmetical 
associations was studied. When two numbers were shown 
one above the other and the observer was told in advance 
to add or subtract, the result came at once or after a rela- 
tively short time. When, on the other hand, the numbers 
were shown with no instructions, the resulting process was 
much delayed, and the observer had a chance to study the 
process of choice. The task or purpose serves to control 
choice just as it does to determine association. The effect 
of the purpose is replaced by the situation and the general 
intentions of the moment in many choices of everyday life. 
It is this that leads one to take an umbrella when the sky 
is cloudy, and a cane when it is clear, as one goes past the 
rack in the hall; to choose a serious volume when one 
comes into the study in working hours, and a novel or the 
newspaper in the period just after dinner. In all these 
things, the choice, while apparently undetermined, is guided 
by the general attitude and the environment. 

More Remote Influences in Choice. — In more compli- 
cated and important instances of choice, the final selection 
is similarly determined, but the controlling influences are 
much more numerous. The final release comes with think- 
ing of the end to be accomplished with the full behef that 
the act is to be carried out. The antecedent processes are 
much like the balancing of decisions in doubt before full 
belief presents itself. First one alternative is thought of, 
then another. After these alternations have repeated 
themselves several times, one finally dominates, is held in 
mind, and the others are by that very fact excluded; the 
decision is made. The forces that favor the possible alter- 
natives are to be found in the instincts on the one side and 
the social forces on the other. They constitute what are 
called the motives. The motives are themselves ordinarily 



THE WILL 531 

quite largely out of consciousness. One knows only that 
one course of action or another is preferable but has no 
knowledge why it is preferred. Carrying this back, we see / 
that of the possible lines of conduct the one is chosen which/ 
proves most attractive. Why it is attractive is determined 
by natural endowment and education. There is no trace 
of what is commonly called will. 

The Will 

Is there a Peculiar Will Element? — A problem much 
discussed since the beginning of psychological theory is 
whether there is a specific quahty or a specific function, 
apart from those outlined above, which can be called the 
will. The earUer writers, always tending to discover a 
separate faculty or force for each of the words in common - 
use, hardly questioned the existence of something of the 
kind, something which was an actual force in decisions and 
an incentive to action. As the direct examination of men- 
tal states began to take the place of speculation with only 
inaccurate observation, fewer and fewer men were able to 
discover this peculiar state. Instead, an ever-increasing 
number of authorities found the final cause of action in an 
idea that was attended to, in an idea of movement with 
the belief that it was to take place, or in the feeling qual- 
ities preceding or accompanying the idea. As more and 
more work was done upon the analysis of the consciousness 
preceding action, the less was there found that was pecu- 
har to this state. 

Recent investigators, Ach and Michotte and his follow- 
ers, have revived the old doctrine in a sHghtly new form. 
In certain of his more comphcated reaction time experi- 
ments, Ach asserts that it is not merely holding the idea 
of the movement in the centre of consciousness that evokes 



532 FUNDAMENTALS OF PSYCHOLOGY 

the movement, but that in addition to this it is necessary 
that the self become momentarily identified with the move- 
ment to be made. At the moment the self is thus identi- 
fied with the one alternative, the choice is made, and the 
action is determined. A somewhat similar statement is 
made by Michotte in connection with a choice between 
operations upon numbers as a result of experiments carried 
on by himself and Priim.^ In a second experiment, also on 
reaction times, conducted with Barrett, ^ measurements 
were made of the time required to choose between two 
liquids and to drink one of them. The liquids represented 
different degrees of pleasantness and unpleasantness. They 
were tested in advance and designated by letters that 
should have no associations other than those which devel- 
oped during the experiment. The observer was to watch 
carefully what preceded the decision and to determine if 
possible what was the deciding factor in his choice. In 
this series of experiments the element of voluntary choice 
seemed less important. In fact, Barrett regarded the re- 
sult as proof that choice is made and executed without 
any pecuHar new activity that could be designated an act 
of volition. Instead, he found that one arranged the tastes 
as they were learned in order of agreeableness; and, when 
they were presented, the value on this scale was an imme- 
diate guide to the choice. The whole choice was com- 
pleted when the Hquid had been given its letter and place 
in the series. He finds that the determinants of the act 
are approximately the same as those we have enumerated 
above. Michotte ^ in reply reasserts his belief in a pure 

1 Michotte and Priim, Etude experimentale sur le choix volontaire et ses 
antecedentes immediates, Archives de psychologie, Vol. X, p. 113. 

2 Barrett, Motivation Tracts and Motivation Forces. 

3 Michotte, A propos de contributions recentes a la psychologie de la 
volonte, Ann. de LTnstitute Super, de Phil., No. ix. 



THE WILL 533 

act of volition which must intervene in all acts of choice, 
whether related to action or not, and after the choice is 
made must again intervene in the execution of the act in- 
volved in the choice. He beheves that the selection of one 
from a group of Hquids of known value tends to render the 
process more automatic, and that this accounts for the 
smaller part played by voluntary choice. 

This difference of opinion between Barrett and Michotte 
is typical of the opposing possibihties in the explanation 
of a voluntary act. On the one hand, emphasis is placed 
upon the more remote underlying conditions ; on the other, 
upon the necessity for discriminating between the alterna- 
tives by holding in mind first one of the motives and then 
the other, and making a positive choice between them. On 
Barrett's interpretation, the motives are effective because 
they appeal to certain instinctive or habitual and social 
traits in the man's nature. On Michotte's, the final de- 
terminant of action is a force or active element which 
serves to make the choice and release the act. On the 
second alternative, the active element is hard to describe, 
is found by only a few men and by them only on rare 
occasions. Although prominent in popular discussions, the 
observation of untrained men, who constitute the chief ad- 
vocates of its existence, is unrehable. Much of the feehng 
of will that the popular mind accepts as evidence of a sep- 
arate faculty is made up of strain sensations, which even 
Michotte would not regard as an essential part of his vol- 
untary act. Viewed from the practical side, it makes very 
Httle difference whether this active element is or is not as- 
sumed. All would agree that when the will acts, it acts in 
the light of the motives; it is an expression of the nature 
of the man; and that in turn is dependent upon his in- 
stincts and training, his immediate purposes and general 



534 FUNDAMENTALS OF PSYCHOLOGY 

ideals. The only question remaining is whether these act 
directly in the execution of the movement, or whether they 
act first upon the will, and that in turn determines the act. 
In view of the uncertainty as to whether the will activity 
exists and what it is Kke if it exists, it seems simpler and 
safer to omit it as superfluous, and to assume that the ob- 
served conditions determine action directly. On that con- 
clusion, 'will' is a term to designate the whole man active, 
or a word used to distinguish between automatic acts and 
those that imply choice and are controlled by the system 
of purposes. It does not necessarily imply any new and 
distinct entity. 

The Will and Freedom. — This result suggests the old 
problem of the freedom of the will, and it may be consid- 
ered here, in spite of the fact that it is at present regarded 
as belonging to ethics rather than to psychology. At first 
sight it seems a logical inference that, if man has no will, 
he cannot be free. This defines the will too narrowly; it 
would restrict it to the something that we could not find 
standing between the motives and the act itself. If we 
regard the will as the sum of the conditions which lead to 
action or to spontaneous action, or even more generally as 
the whole man active, the question cannot be disposed of 
so summarily. From this point of view, the answer as to 
whether the man is free depends very largely upon how we 
define 'the man.' We have seen throughout that many of 
the determinants of all mental action, and particularly of 
voluntary action, are to be found in his instincts, in the 
way he has been affected by education and by the society 
in which he has hved, by his nature and nurture in the 
broadest use of both terms. If one is to oppose these ex- 
ternal forces to the man himself, a good case could be 
made for the statement that the man is largely determined 



THE WILL 535 

by forces outside of himself. But if one make the division 
between the man and all of these factors, if one take away 
from the man all that he has learned, all the controlHng 
forces of society, and all of his natural endowments, his 
instincts and innate tendencies, only a rag of a man would 
be left; most that is pecuKarly himself would have disap- 
peared. It is altogether more satisfactory and truer to the 
facts to regard these influences as included in the man, to 
think of him as in part at least the product of his heredity 
and environment, for this is the man as we know him. To 
divide the controlling forces into two groups, one external, 
the other internal, one environmental, the other personal, 
has never been attempted; and no two psychologists agree 
where the division would come. Oppose the man as he is, 
to external forces, and he must be said to control his own 
acts. They are the expression of the whole man, and he 
is free to do as he chooses. One may put the solution of 
the problem in another way by asserting that man is free 
to do what he desires, but his desires are the outcome of 
his instincts and environment and over these he has httle 
control. In other words, the question is largely one of 
classifying facts and of defining terms. The facts them- 
selves are accepted by all. 

In practice, acceptance of one theory or the other makes 
httle difference. What one generally does is to think of 
one's self as a free agent in every respect, and of every one 
else as rigidly determined by environment and education. 
It is only when one takes the objective attitude toward 
one's own acts, that one tries to trace them to their condi- 
tions. Probably this assumption works best in practice. 
The new tendency to regard man as the product of his en- 
vironment has led to improvement in social conditions, to 
the recognition that mankind in the mass may be improved 



536 FUNDAMENTALS OF PSYCHOLOGY 

if one will but begin with remedying the fundamental con- 
ditions of Hving, that changing his environment is better 
than talking to him. Improvements in education, in hous- 
ing conditions, and all the multitude of laws for bettering 
the environment of the poor, are due to the growing tend- 
ency to regard the environment as responsible for the ac- 
tions of others. On the other hand, the behef in one's own 
freedom probably gives added initiative, and increased 
recognition of individual responsibility that would be lost 
were one to think of one's self as a mere hnk in the world 
chain. However, the instinct of self-assertion is too strongly 
embedded to permit acceptance of any theory to change 
the aggressive individual into an inert one. 

Probably the difference in the attitude towards crime 
and the criminal more clearly represents the effects of the 
two theories. On the older free-will doctrine, the criminal 
was altogether responsible for his acts. He would or he 
would not carry out each act. There could be no control 
of crime, because no one could tell when an individual 
might decide to commit one. The other theory looks upon 
the criminal as the product of his heredity and of his en- 
vironment, in much the same way that a sick man is the 
victim of circumstances. In the extreme form, the whole 
problem is one of removing the causes of crime, as the 
control of health is one of removing the causes of disease. 
The attitude toward punishment changes similarly. If 
the man is free to be a criminal or not to be, the only 
value of punishment is to get even, to measure the crime 
and make him suffer as he has made others suffer, 'an eye 
for an eye.' On the other theory, punishment is merely a 
means of reform. It gives the criminal a motive for re- 
fraining from crime, it may give him a chance to form new 
habits, or even to learn some new trade or obtain some 



THE WILL 537 

other means of support that shall make crime unnecessary. 
In the worst cases, it is a protection to society by remov- 
ing the criminal to a place where he can do no harm. In 
any case the idea of vengeance, essential to the older view, 
plays no part. When it is considered that a large percent- 
age of criminals are mentally deficient, have an intelhgence 
no greater than a child of ten, the modern theory has even 
more weight. The final outcome of the two theories is ap- 
proximately the same; but the methods of inflicting the 
punishment and the attitude while carrying it out are al- 
together different. On the whole it may be said that the 
problem of the freedom of the will has been outgrown 
rather than solved. The present attitude toward the 
world and man's place in the world leaves no room for the 
problem, instead of deciding which solution is the correct 

one. 

REFERENCES 

Ladd-Woodworth: Principles of Physiological Psychology, 

pp. 542-565. 
Ach: Ueber die Willenstatigkeit und das Denken. 
Swift: Mind in the Making. 
Balr: The Acquirement of Voluntary Control. Psych. Review, 

Vol. VIII, pp. 474 ff. 
Woodworth: Le Mouvement. 



CHAPTER XVIII 

WORK, FATIGUE, AND SLEEP 

Very important for the practical life of industry and even 
for the health of the individual is the problem of the 
natural course of work, particularly the length to which 
work may be carried before the individual becomes in- 
capable of more work, or will suffer injury either immedi- 
ately or ultimately. In industry, and probably in mental 
work too, there are limits beyond which one cannot work 
effectively. Time spent in work would, beyond these 
limits, much better be spent in rest or recreation; even if 
one considers only the accomplishment in a given time, with 
no thought of the effort required, or the ultimate health of 
the worker. 

Work 

The Curve of Accomplishment. — The course of work, 
or the curve which indicates the accomplishment at differ- 
ent intervals during a period of work, is fairly well made 
out both for purely mental work and for the combination 
of physical and mental work which is found in the ordinary 
factory procedure. At the very beginning there is usually 
a rapid dechne in accomplishment. This is followed by 
a gradual rise to a maximum moderately early; and from 
that point there is a decline until just before the end, when 
a brief rise occurs for the last few minutes. If rest periods 
intervene, they are followed by a rise, succeeded by a fall 
at a more rapid rate than before the rest. The duration 
of the different phases varies with the total length of the 

538 



WORK 539 

period of work, with the individual, and with the character 
of the work. In one or two instances of mental work under 
considerable incentive, there was no appreciable change in 
the curve. In one in which mental arithmetic was the 
work used, the decrease during twelve hours of continuous 
work was only about fifty per cent, and at the end the work 
was at a rate above that of the ordinary individual. 

In the tests of mental work made by Kraepehn and his 
students, of two hours' duration, the point of highest ac- 
complishment was from fifteen to forty-five minutes after 
the work began, with a gradual fall to the end. In records 
of output of work in various factories, the high point seems 
to be between nine and ten o'clock, when the work begins 
at eight; then there is a fall until noon; and after the noon 
hour an increase; with a decrease to the end of the day. 
As further evidence that there is a somewhat regular curve 
of capacity in the day's work in the factory, is the time of 
occurrence of the maximum number of accidents. An acci- 
dent is due as often to mental as to physical fatigue. Failure 
to attend or to remember, or lack of judgment in estimating 
the position of knives or other parts of a machine, is more 
frequently the cause of an injury than mere physical 
fatigue. Accidents show a regular increase until eleven 
in the morning, after which the curve is constant or shows 
a very slight decrease in the last hour in the morning. It 
falls after the noon hour to about the same level as in the 
first hour in the morning, and rises rapidly and continuously 
during the afternoon. 

We have then in the course of work, particularly work 
that demands mental activity, as almost all work does, 
a quick fall for the brief period at the beginning, then a 
gradual increase in accompKshment for a time, followed 
again by a decrease that is checked only by a short rise at 



540 FUNDAMENTALS OF PSYCHOLOGY 

the end, if the worker knows when the end is to be. A 
rest of sufficient duration is followed by increased output, 
and then ensues a more rapid decrease than in the period 
before the end. 

Analysis of the Curve of Work. — In the analysis of this 
standard curve of work it is assumed that the capacity 
at a given time is determined by a number of cooperating 
independent factors. The gne most frequently mentioned 
ia fatigue, which is assumed to increase with the time spent 
in work. The second, practice, counteracts fatigue, since 
it also increases capacity as work increases in a somewhat 
regular course. Practice increases more rapidly at first, 
and then less rapidly. Practice is allied to habit as an 
adjustment of the nervous system to a new situation, and 
constitutes what we call skill. It is assumed to reach a 
maximum at some time, although it is probable that new 
conditions of work or a new attitude towards work may 
produce an improvement even after long periods of training. 
It can be said, however, that practice will make work more 
easy and effective, that it increases rapidly at first and then 
more and more slowly as work is continued. 

The initial fall and terminal increase are due to a tem- 
porary incentive. The individual begins with a firm in- 
tention of doing his best, and does so for a few strokes. 
This special incentive wears away quickly, and with it 
there is often a fall in output immediately after work begins. 
At the end there is a similar speeding up to make a good 
showing for the finish. This is not necessarily conscious, 
but the very fact that the end is in sight serves as an 
incentive and speeding up takes place automatically, just 
as the goal in a race calls out a final increased effort. A 
fourth factor is inertia. In most types of work it takes 
a little time to reach the best speed; and when once started 



FATIGUE 541 

work is continued at approximately the same rate. This 
is most evident in the fact that when the work is inter- 
rupted by a rest, some time is required to reach the same 
speed as before the interruption. It makes a shorter 
rest within Umits more effective in restoring efficiency than 
a longer one. 

Fatigue 

Is Fatigue Real? — The most important of these factors 
is fatigue. By fatigue we mean a reduction in the capacity 
for doing work which comes as a result of work. This 
definition is open to criticism from the fact that not all 
work seems to be followed by a reduction in capacity even 
for doing the same kind of work. Kraepehn explained 
this as due to the counteracting effect of practice and 
inertia. Others have held at times that there is no mental 
fatigue, but that the working individual merely becomes 
bored, not tired, that the central nervous system does not 
lose capacity with work. The results of Aral ^ are cited 
as evidence that 'mental work may go on indefinitely 
without noticeable diminution in output. We can probably 
reconcile the facts adduced in favor of the two views by 
assuming, as there is good reason to do, that organically 
work produces a lessened capacity in the organism, but 
that this is automatically compensated for by extra effort. 
This keeps the individual working at about the same speed, 
and possibly with just as few mistakes in spite of reduced 
physical capacity. The awareness of fatigue is itself an 
incentive that in many individuals spurs to new effort. 
In this respect fatigue is just Hke distraction; and Hke 
distraction it may at times over-compensate, so that an 
individual works even more rapidly when fatigue has set 

^ Arai, Mental Fatigue : Columbia University Contributions to Education 
No. 54. 



542 FUNDAMENTALS OF PSYCHOLOGY 

in. That fatigue is a real factor is evident from the fact 
that occasionally a worker will keep up the same speed 
for a considerable period and then will stop suddenly with 
what seems to be a collapse. Dodge has shown this in 
connection with fatigue of eye muscles, and we find some 
evidence of it in the daily work, particularly in diseased 
individuals. It must be said, however, that ordinarily 
the disagreeableness of work after fatigue is pronounced is 
a sufficient safeguard against carrying work to the point of 
collapse. 

While fatigue is a real accompaniment of mental as well 
as of physical work, the fact that fatigue does not increase 
regularly with the amount of work makes it difficult to 
determine what the condition of the individual is at any 
time as regards fatigue. One may obtain a general in- 
dication from the amount of work done as compared with 
the average accomplishment, or by introducing soms 
special test or standardized task that shall be closely 
related to the work being done. The objection to the 
latter is that one can nearly always under incentives spur 
one's self to a maximum rate for a brief period, and the 
test becomes an unsatisfactory criterion of the condition. 
Dr. Lewis has found indication that the glycogen content 
of the blood is increased during fatigue; and Dr. Griffitts 
and the writer have found indication of a lowered blood 
pressure after severe mental work. It is highly desirable 
to find some such test of condition that shall be independent 
of work done, that may be used to determine when the 
individual has worked enough. On the whole, it seems 
assured that there is a real fatigue as a result of mental 
work. Whether one can define fatigue as the reduced 
capacity for doing work as a result of work or not, is com- 
pHcated by the fact that diminished physical capacity is 



FATIGUE 543 

compensated for by greater effort. If capacity is under- 
stood as a physical capacity, only indirectly indicated by 
accomplishment, it may stand. It is at least as satis- 
factory as any formula that can be suggested. 

The Physiological Nature of Fatigue. — When we turn 
to ask what the cause of fatigue may be, we must approach 
the problem from the physiological side. The first studies 
of fatigue were made on the muscle and nerve of a frog. 
If a muscle with the motor nerve that excites it be dis- 
sected out of a frog, and hung so that the muscle supports 
a lever that will write upon a drum, the amount of the 
contraction will be recorded upon the drum. If the nerve 
be stimulated, the muscle will contract; as the stimulation 
is continued the contractions become shorter and shorter 
until they finally cease. The causes of fatigue in this 
simple system are found first in the breaking down of the 
point of connection between nerve and muscle, the end- 
^late. This is shown by the fact that after the muscle can 
no longer be stimulated through the nerve, it will still 
respond when stimulated directly. 

Continued direct stimulation of the muscle will com- 
pletely fatigue the muscle. This indicates that there is a 
real fatigue of the muscle proper. The nature of this 
change is due in part to the accumulation of products of 
degeneration, as can be seen from the fact that after the 
muscle has stopped acting once through fatigue, it will 
respond again in almost full amount after it has been 
thoroughly washed in a dilute solution of salt. There is 
also exhaustion of the stored nourishment in the tissue, 
but this seems to come later than the inhibition of the 
capacity for action, due to the accumulation of waste 
oroducts. In addition to the waste products that accumu- 
late in the muscle itself, investigations of animals working 



544 FUNDAMENTALS OF PSYCHOLOGY 

as wholes indicate that toxins appear in the blood and 
may be carried to any part of the body and affect tissues 
of all kinds. An old experiment of Mosso showed that 
blood transfused from a fatigued dog to a rested one pro- 
duced in him many of the effects of fatigue. While later 
experiments do not altogether confirm the Mosso method, 
other methods do indicate an accumulation of toxins in the 
blood as a result of continued work. The toxic effects 
seem to be diminished or overcome by the secretions of 





Fig. gy. — Changes in the nucleus as a result of fatigue. (^4) and (B) are both 
from the spinal ganglion of a cat. (A) shows the resting condition, (B) a cell 
after electrical stimulation of its nerve for five hours. The nuclei in (B) may be 
seen to be much smaller and to be very irregular in outline. (From "American 
Text-book of Physiology," after Hodge.) 



adrenal glands. Animals in whom the glands are removed 
indicate a much greater effect of work, and are also more 
influenced by injections of fatigue products than are normal 
animals. This may explain why Dr. Lewis found an in- 
crease in glycogen in the blood following mental work. 
It is possible that the adrenal secretion nullifies fatigue 
indirectly by increasing digestion and stimulating the liver 
to an increased secretion of glycogen. 

Fatigue of Central Cells. — In the body as a whole one 
more factor is at work, and this is the possible exhaustion 



FATIGUE 545 

of the nerve cell. Hodge found in a bee that after a full 
day's work, the nucleus of the ganglion cells was very much 
reduced in size, and the walls of the nucleus were irregular 
in shape as if collapsed, as compared with the same cells 
in the morning. Electrical stimulation of the cells from 
the spinal cord of the cat for five hours produced much the 
same effect. These changes in the cell bodies of nerves, 
the accumulation both in muscles and in the blood of waste 
products which act as poisons, the exhaustion of the tissues 
and of the muscles together constitute the physical changes 
in fatigue. These effects do not all act to reduce the 
capacity. In the isolated muscle, even, the first effect of 
fatigue is to produce unusually large contractions. Ap- 
plication to the muscle in small amounts of waste substances 
from another muscle increases the amount of contraction 
even with constant stimulus; and the products of the 
muscle itself have the same effect. Fatigue products first 
increase the excitability of a muscle, and then diminish 
and finally destroy it. 

Consciousness of Fatigue. — On the mental side, con- 
sciousness of physical fatigue is marked by sensations of 
pain or at least of discomfort from the muscles. The 
lactic acid and other chemicals released by repeated con- 
tractions apparently stimulate the nerves of pain in the 
muscles directly and give rise to the sensations. More 
general feelings of lassitude may be due to the reduced 
tonus of the muscles or to the slowness with which. muscles 
respond to stimulation. That there are complexes of 
sensations which go with the condition we know as fatigue 
is evident to every one. The immediate sensations are 
probably to be found in the excitations of pain nerves in 
the muscles. The remainder is probably an inference 
from the reduced capacity for action. It has been sug- 



546 FUNDAMENTALS OF PSYCHOLOGY 

gested that mental fatigue is largely an inhibition of action 
from the distracting effect of these sensations. This may 
account for part of the reduced efficiency, although, as was 
seen, distraction also tends to increase efficiency on occasion. 
Mental Fatigue. — What may constitute mental fatigue 
apart from bodily fatigue, is not as yet altogether agreed 
upon. Mental work has always an incidental physical ac- 
companiment. Muscles are always active in some degree. 
That they are sufficiently active to account for the effects 
of mental work is extremely unlikely. Certainly mere 
thinking on an abstruse problem is harder work than a 
game of golf, for example, which must involve vastly more 
muscular contraction. Some considerable activity of the 
cortical neurones must be involved in thinking, but we 
have only indirect evidence of the amount of change in 
energy or chemical decomposition involved, and these point 
in opposite directions. Atwood could find no increase in 
the bodily metabolism during mental work. Dodge, on 
the contrary, found that mental work had about the same 
effect on the circulation as physical work of average in- 
tensity. Merely opening the eyes and passively observing 
a room produced a change equivalent to that produced by 
lifting a pound weight; and hard reading was found to be 
the equivalent of a genuflection. Fatigue might be due to 
exhaustion of the neurones directly, or it might be due to 
the waste products that are discharged into the circula- 
tion and reach the muscles and other parts of the brain. 
No one has as yet demonstrated the existence of either 
change. The nearest approach is the discovery by Dr. 
Lewis of increased amounts of glycogen in the blood as an 
accompaniment of mental work. The indirect evidence of 
mental fatigue is found, first in the feeling of lassitude that 
follows upon mental work, second in the decrease of the 



FATIGUE 547 

amount of work as time passes, third in the after-effects 
of long-continued excess of mental work in inducing loss of 
weight, and the various physical and mental symptoms 
that accompany what is called a nervous breakdown. Alto- 
gether these suffice to indicate the reaHty of mental fatigue 
and its general similarity to physical fatigue. 

Bodily Accompaniments of Fatigue. — If we consider 
the action of fatigue, mental or physical, in the conditions 
of everyday hfe, we must assume that each bit of work 
has the effect of decreasing the nourishment stored in the 
tissues, of increasing waste products in the tissues them- 
selves and in the blood, and that if it be muscular work 
continued for a long time on one muscle it may decrease 
or destroy the connections at the end plate, and finally ex- 
haust the nucleus of the cells. The first effect of these 
changes is probably to increase the irritability of the 
muscle, which increases its capacity. These processes, 
through the excitation of nerves in the muscles, produce 
reflexly an increase in the rate of the heart, and of respira- 
tion, thus supplying more oxygen to the red blood corpus- 
cles, and a larger flow of blood, wdiich both increases the 
nourishment at the service of the muscle and washes the 
waste products out more quickly. After a time the ad- 
renal glands are affected, and these increase the supply of 
glycogen from the liver and also affect the activity of the 
circulatory system. For a considerable period these auto- 
matically induced processes compensate for the extra work. 
The capacity of the organism is increased to keep up with 
the demand. 

All these increased activities make a demand upon the 
reserve; and while the reserve is sufficient to keep the out- 
put at a maximum over a long period or even to increase 
it, it is alway?- at the expense of extra effort. In the long 



548 FUNDAMENTALS OF PSYCHOLOGY 

run there must come an end. Unless the demand is very- 
great, the pain of aching muscles and the other discomforts 
of exhaustion bring the work to a stop. It is possible 
under great necessities to continue until exhaustion is 
complete and sleep or other forms of unconsciousness en- 
sue to put an end to the work and permit recovery to be- 
gin. Only very rarely, as in a strenuous military cam- 
paign, or the work of a mother with a sick child and the 
necessity of earning a hving, do we see this stage reached 
in practice. Usually boredom or the unpleasant sensations 
that accompany fatigue induce one to rest, long before this 
stage is reached. This is still more the case- with mental 
fatigue. Here the fatigue from one position, if one is writ- 
ing, or the poor quality of work will make the further ef- 
fort useless, or will furnish an excuse for turning to a more 
pleasant undertaking. In mental work, also, the effects of 
the work seem at times to act as a stimulant. When writ- 
ing or much interested late at night, work seems to go 
faster and to be pleasanter than in the earlier part of the 
day, when fatigue should be much less. That this feehng 
is not an indication of work without fatigue is evident 
from the after-effects, the likelihood of a sleepless night 
and of an incapacity for work the next day. Both mental 
and physical work and the combination of the two that is 
seen in industry bring with them a decreased capacity for 
work, although that may be concealed by the compensat- 
ing increased activity. Work beyond a certain point is in- 
jurious to the individual in that it shortens the period of 
activity, and shows its effect in the diminished output of 
the next day. It is a disadvantage in industry for the 
day-to-day accomplishment. 

Fatigue in Industry. — Numerous practical experiments 
have shown that lessening the hours of work, even with no 



FATIGUE 549 

reduction in wages, is a profitable change for employer and 
worker alike. The Zeiss works in Jena, numerous muni- 
tions factories under the control of the war board in Great 
Britain, and several cases in America show that reduction 
from a ten- to an eight-hour day could be made with an 
actual increase in the output. We have no right to dog- 
matize as to the optimum working period. Too much de- 
pends upon the kind of work, the good will of the workers, 
and other conditions which are either not directly under 
control or are not known as yet to make it possible to be 
certain as to the correct hours for any industry, to say 
nothing of industry in general. For our purposes, the evi- 
dence is sufficient to indicate that there is a hmit of work- 
ing time beyond which it is not profitable to go. Probably 
this is on the average near the eight-hour day. Slower 
work, spoiled products, accidents, and the gradual deteri- 
oration in the operatives, set a definite hmit to the profit- 
able hours of work. 

The Limits of Effective Work. — It is difficult to deter- 
mine exactly where the limit lies. The output, we have 
seen, is no infallible criterion, because when under the in- 
fluence of strong incentives, work may continue undimin- 
ished when fatigue is severe. The sensations and other 
direct mental signs are also far from infalhble. In many 
cases, again under incentives, one feels that work is a 
pleasure, when a sleepless night, or a reduced capacity next 
day, will be the penalty for continuing. On the other 
hand, one frequently feels little hke working when per- 
fectly capable of doing it. One may have a stale feehng in 
the morning, spend some time in wondering whether one 
really ought to work that day, or even fear that the work if 
done will be below standard, and then find when one actually 
warms up to it that quaHty and quantity are normal or better. 



550 FUNDAMENTALS OF PSYCHOLOGY 

It would be highly desirable to discover some index of 
the condition of the individual that might be used by em- 
ployer, or teacher, or . physician, to determine the point 
where work should stop. Attempts have been made to 
obtain one. The writer has experimented with the time 
that one may see a faint hght, and has found that the time 
of visibihty changes with the amount of work done. With 
Dr. Griffitts he recently found indications that there was 
a reduced blood pressure after mental work. Lewis, as 
was said, had found an increase in the glycogen in the 
blood. While the increased glycogen is probably a com- 
pensation induced by fatigue, a sufficient amount or a de- 
crease after increase might be made a sign of the point 
where work should stop. Changes in heart rate, in blood 
pressure sitting and standing, have been suggested. One 
must probably find a fatigue index in some of these indi- 
rect measures rather than in the output or the sensations, 
or any of the more direct changes. Long study will be 
necessary to determine at just what point in the develop- 
ment of any one of these indices, work should stop. Ob- 
servation of the changes in the sign chosen in connection 
with the after-effects of fatigue and the capacity for work 
over a long period must be exhaustive before a useful de- 
termination may be made. 

General Rules for Effective Work. — Meanwhile certain 
general rules can be given which are helpful in the ar- 
rangement of work. One must not expect to avoid fatigue. 
Fatigue as a group of sensations from the muscles or a feel- 
ing of lassitude from long mental work is an inevitable 
accompaniment of all activity. Only when it becomes ex- 
cessive is it even a signal to stop. As a tendency to an ex- 
haustion of the tissues even, it is still not injurious, for the 
deficiency is quickly restored by rest, and use is essential 



FATIGUE 551 

to growth, or even to health. All that one can ask is that 
fatigue should be kept within the Hmits that permit of 
quick recovery during the same day if possible, and will 
certainly give complete restoration after a night of rest. 
How long this shall be for the individual must be deter- 
mined empirically. Usually the effective working period is 
well within the hmits that are demanded by health. Prob- 
ably within this effective time are the hmits set by the dis- 
comfort of sensation, or boredom, or the conventions of the 
hours that shall be devoted to work. In practice few stu- 
dents overwork, and those who do are the weaker ones. 
For industry, the hours are set by the length of day most 
profitable to the employer. This, when all the facts are 
understood, will be found well within the physiologically 
determined Hmits of capacity. 

The Economical Periods of Work. — The most econom- 
ical period of work is that in which one obtains all the ad- 
vantages of continued work without going on to the point 
of fatigue. It is of course impossible to give any general 
rules that will apply to all kinds of work and to all people. 
How much work may be done depends upon the nature of 
the work and upon the strength of the individual. The 
fact that one does more after working for a httle time than 
when one first begins holds universally. How long one 
should continue after the effects of fatigue are greater than 
the benefits of practice, depends upon the kind of work and 
the practical necessities for its completion. Fatigue itself 
is not to be avoided, for the lesser degrees wear off in a 
short time and are entirely overcome by a night's sleep. 
The poor work that results when fatigue is too great makes 
effort unprofitable, and the after-effects in the form of 
overwork may have such serious results as to put a pre- 
mium upon avoiding them at all reasonable cost. 



552 FUNDAMENTALS OF PSYCHOLOGY 

The Best Period for Rest. — To know how long to rest 
between periods of work is as important as to know when 
to stop. Results of experiments indicate that the length of 
the rest that should be introduced between the periods of 
work depends upon the length of the previous work and 
upon the character of the work. The rest should be long 
enough to permit recovery from fatigue, but not so long as 
to lose the mental momentum. After long periods of work, 
two hours or more, the most advantageous intermission is 
approximately fifteen minutes; for relatively short periods 
five minutes has proved itself most satisfactory. Longer 
periods waste too much time, and cause a loss of inertia 
and of practice that is not compensated for by recovery 
from fatigue. Shorter intermissions merely cause loss of 
inertia without any compensating rest. In severe physical 
work in industry it has been found as important to insist 
upon proper and sufficient periods of rest as upon sufficient 
periods of work. In Taylor's first experiment in efficiency 
management, which consisted in a study of the best meth- 
ods of lifting heavy pigs of iron, it was found that if the 
men followed their natural bent, working with the pros- 
pect of a bonus, they would work too continuously, and it 
was necessary to prescribe rest periods which should be 
rigidly observed, if the most work was to be accomplished 
in a day. Mental work requires similar rest periods for 
the maximum performance, but the best periods for the 
different types and degrees of work have not been deter- 
mined accurately. 

Change of Work No Rest. — Several facts that have 
been suggested by experiments are contrary to the com- 
mon assumptions of many people. For example, it is be- 
lieved usually that one may rest through change of work, 
— that if one has been tired by mental work of one sort it 



FATIGUE 553 

is not necessary to rest altogether, but by turning to some- 
thing else one may become rested through the change. 
The one important investigation on this point indicates 
that the everyday assumption is not in harmony with the 
facts. An hour's work learning nonsense syllables, fol- 
lowed by a half hour's practice on mental arithmetic, with 
a return to the nonsense syllables, rests one no more than 
a continued period of nonsense syllables. This is on the 
assumption that learning nonsense syllables is no more 
difficult than mental arithmetic. If one turns from a more 
difficult to an easier task, one will of course not be so tired 
as if one had continued with the more difficult. So far as 
these results can be accepted, it seems that all sorts of 
mental fatigue are of the same kind, and that it is not pos- 
sible to rest one function while exercising another. There 
is so much in common between the different mental opera- 
tions that all become tired together. It is possible that 
the commonly accepted opinion to the contrary is due to 
the greater interest one may have in a new task. One or- 
dinarily turns from a task only when obstacles have pre- 
sented themselves or when for some reason the work has 
become uninteresting. It is possible that the greater in- 
terest in the new work and consequent greater effective- 
ness are mistaken for recovery from fatigue. 

Mental and Physical Fatigue One. — Very similar is the 
attitude toward the problem of the relation between men- 
tal and physical fatigue. It is generally beheved that one 
may rest from mental work while exercising, but experi- 
ments indicate that capacity for mental work is decreased 
by physical work, if it is too difficult. If one takes a vigor- 
ous run or other severe exercise between two periods of 
the same sort of work, as in the experiments mentioned 
above, the capacity for mental work is diminished rather 



554 FUNDAMENTALS OF PSYCHOLOGY 

than increased. Here as before the effect will depend upon 
the severity of the task. If the exercise be mild, one will 
rest relatively, just as one does during less difficult mental 
work. In fact, the whole question of work and fatigue is 
relative, as one never rests absolutely except during sleep, 
and even then there is merely gain of repair over waste, 
not absolute quiescence of all functions. The identity of 
mental and physical fatigue has been demonstrated 
many times, both that mental work induces physical fa- 
tigue and that physical work induces mental fatigue. One 
cannot do severe mental work effectively after a hard day 
of physical labor, and experiments show that one is less 
capable of physical labor after hard mental work. This 
general identity of mental and physical work and fatigue is 
being recognized by the physician. A patient suffering 
from overwork as a result of too much study or worry is no 
longer advised to take much exercise, but is put to bed or 
given very Uttle, easy exercise. Of course this does not 
imply that exercise is not beneficial in health. Exercise is 
essential to the development and health of the body, and 
needs no justification. One should not expect to be able to 
work immediately after exercise, but in the long run the 
effects of exercise are beneficial. 

Morning and Evening Workers. — Another interesting 
result of recent investigations is that there are daily 
rhythms of capacity for work, that every one has a certain 
part of the day during which he has greater capacity. Ac- 
cording to one authority, men divide naturally into morn- 
ing and evening workers. The one group are at their best 
early in the morning, the other group do not reach their 
full capacity until toward evening, — the amount and ac- 
curacy of their work increases steadily through the day. 
It has not been determined whether the difference is in- 



FATIGUE 555 

nate or the result of habit; but in an adult accustomed to 
mental work, one habit or the other is always readily dem- 
onstrated, even if the individual himself is unaware of it. 
Evidently one should take advantage of the daily rhythm 
by devoting the best part of the day to the more difficult 
tasks. There are also minor ups and downs in capacity 
during the day which may be confused with rest and fa- 
tigue in experiments. 

General Remarks on Work. — It should be added that 
the measurements of fatigue upon which these statements 
rest are derived from ordinary routine work under no par- 
ticular incentive other than to do one's best. It is certain 
that a sufficiently strong desire would at any stage have 
brought the rate of work back to the maximum, at least 
for a little time. While the amount of work that will be 
accomplished depends very largely upon the incentive, it 
does not follow that fatigue is not real and a factor to be 
considered in the arrangement of the day's routine. The 
results that have been given hold for the course of ordi- 
nary work where the incentive is constant and not particu- 
larly strong. If the incentive is increased, the absolute 
times given would all be increased, but the relative values 
\vould still remain approximately the same. There would 
still come a time when the amount and accuracy of the 
work would be reduced to a point where work did not pay. 
Work done willingly and cheerfully under suitable incen- 
tives is apparently less fatiguing in the long run than a 
smaller amount accomplished under unfavorable condi- 
tions. One may even agree with James that in moments 
of exaltation one may perform at a rate far above the or- 
dinary level without permanent injury, and at the same 
time accept the results of experiments under ordinary con- 
ditions as a guide for daily Hfe. 



556 FUNDAMENTALS OF PSYCHOLOGY 

Sleep 

The natural consequence of fatigue, and closely related 
to it in theory, is sleep. Curiously enough in spite of the 
frequency of occurrence of the phenomenon, sleep is one of 
the least understood of the psychological and physiological 
processes. We know relatively little of the reasons why 
one goes to sleep, or what takes place when one does go to 
sleep. As in fatigue, one may develop a circulatory the- 
ory, a chemical theory, a central nervous theory, and a 
general reaction theory, not to mention attention theories 
and a dissociation theory. It was long held that sleep 
could be explained by a decrease in the circulation of the 
blood in the brain, which rendered the brain less capable of 
action, and so caused unconsciousness. It is hardly likely 
that the reduction in circulation should be so complete; if 
it were, there would be no rebuilding of the tissue. Dr. 
Shepard and others have shown that there is an increase 
rather than a decrease in the volume of the brain in sleep. 
The only suggestion of confirmation of the theory is that 
the walls of the blood vessels of the brain are very much 
relaxed in sleep, so that waves of respiration are very much 
greater than in the waking state. This is more likely to be 
an effect than a cause of sleep. 

Chemical Theories of Sleep. — The chemical theory is 
that the products of fatigue accumulate in the central cor- 
tical cells and reduce or destroy temporarily their capacity 
for action. Pieron has results which lead him to beUeve 
that a toxin is developed in the blood by loss of sleep 
which is different from that developed by fatigue. When 
blood from an animal that has been kept awake for a long 
period is injected into the fourth ventricle of the brain of 
another animal of the same species, it shows all of the signs 



SLEEP 557 

of sleepiness of the animal from which the fluid is taken. 
Fatigue products from the muscles do not show the same 
effect. Pieron's belief is that the toxin of sleep is devel- 
oped by the action of the cells of the cortex, and might 
constitute a specific result of mental work for which we 
were seeking in an earlier section. 

Nervous Theory of Sleep. — The central nervous system 
theory was connected with the synapses. In sleep the nerve 
currents run very slowly, and this indicates increased 
resistance at the synapse. One early theory was that sleep 
was due to the withdrawal of the dendrites, in the same way 
that the amoeba draws in its processes when asleep. In 
animals killed by an anaesthetic the dendrites were retracted 
in this way. The amoeba theory of the synapses has been 
given up, more because it was difficult to understand why 
an animal should be aroused from sleep by outside stimuh 
than because it did not harmonize with anatomical observa- 
tions. The theory explains sleep, but would permit only 
spontaneous waking. 

Sleep an Instinct. — The most recent theory is that 
sleep is an instinctive reaction to definite sets of stimuh. 
Several analogies may be developed which are in Hne with 
this assumption. The first is the long hibernation or winter 
sleep of many animals. This seems to be altogether or 
largely a response to the season, or to temperature and 
other changes that come with the seasons. Another re- 
sponse of quiescence to a positive stimulus is the death- 
feigning instinct of many feeble animals, such as the 
opossum, and the young of the terns. To a strong stimulus, 
they respond by loss of the capacity for movement, which 
sometimes is accompanied by loss of muscular tonus. 
Claparede some years ago and Rivers recently have sug- 
gested in slightly different forms that sleep is a response 



558 FUNDAMENTALS OF PSYCHOLOGY 

of a similar character, that serves to make possible the 
recuperation of the individual. During sleep cessation of 
all activity, and increased circulation in the cortex, and 
possibly in other important organs, stop use and supply 
materials for rebuilding tissues. 

To say that sleep is an instinct does not explain it until 
we can discover what the nature of the reaction may be 
and what causes it. The stimulus for sleep varies much 
under different conditions. Li most cases it is a response 
that recurs at approximately the same time of day. In 
this animals differ widely. Some instinctively respond by 
sleep to the coming of darkness, others to the coming of day. 
The difference is altogether instinctive. In man the instinct 
is subordinated to habit, and the time of approach of the 
response and the length of sleep vary with the earlier life 
and occupation of the individual. In addition the imme- 
diate stimulus may be presence of feelings of fatigue, buL 
on the other hand too much fatigue may prevent sleep. 
Monotonous stimuli are also frequently followed by sleep. 
Absence of stimulation acts as a monotonous stimulus. All 
stimuli for sleep work best when accompanied by sugges- 
tion. If one expects to sleep, sleep is almost certain, unless 
other circumstances are unfavorable. Excessive fatigue 
will also finally result in sleep, but can be fought off volun- 
tarily, or under the influence of strong stimuli, for a long 
time. Animals kept awake by strong stimuK will die after 
a few days. Loss of sleep is more quickly fatal than is 
starvation. Fatigue seems to be an inducing condition, and 
sleep is more and more likely as fatigue advances, provided 
other conditions are favorable. It seems to be a contribut- 
ing condition rather than the immediate cause, until it 
becomes very intense. The final collapse from exhaustion 
seems to be not quite the same as the normal sleep in 



SLEEP 559 

moderate degrees of fatigue. It is more like an intoxication. 
The observed phenomena of sleep seem to combine most 
if not all of the factors that have been suggested as the 
causes of sleep. ^Measurements of the course of sleep show 
that there is a constant increase in the depth of sleep as 
measured b}' the strength of the stimulus required to waken 
the sleeper, during the first hour and a half. After that 
there is a diminution up to the time of waking. Accompany- 
ing this there is a decrease in blood pressure during the first 
part and a rise in the latter part. On the nen,-ous side, the 
reduced stimulabihty has been interpreted as due to an 
inhibition of the cortical centres; it has also been regarded 
as a mark of dissociation, for certain of the phenomena of 
sleep walking and dreams seem alhed to h}-pnotism, and 
similar processes, that are explained as due to dissociation. 
One may think of sleep, then, as a reaction in which the 
central nervous system has its acti\dty inhibited, and the 
action of the lower centres is checked, which carries -^-ith 
it changes in circulation and respiration and prevents the 
acti\"ity of muscles and glands. The net result is a state 
in which recuperation is possible. It is also a self-terminat- 
ing process. As the tissues are restored, and toxins removed 
from the tissues and from the circulation, the susceptibihty 
of the central nervous system is restored, and any stimulus 
is more hkely to induce the acti^"ity of the cortex which 
brings with it the release of inhibition and restoration of 
the functions of circulation and respiration. 

REFERENCES 

Lee: The Human Machine. 

Muscio: Lectures in Industrial Psycholog}-, pp. 45-88. 

Myers: The Mind and Work. Chapter II. 

Shepard: The Cerebral Circulation in Sleep. 

H. PiEROx: Le probleme ph3'siologique du sommeil. 



CHAPTER XIX 

THE SELF 

In our ordinary life and in much of scientific psychological 
discussion frequent use is made of the term ' self ' . For popu- 
lar thought the most important part of consciousness and 
of the world as a whole is found in the ' L' To it practically 
everything is referred. It is regarded as the effective agent 
in most of the acts of the individual, and is the source of 
most of his emotions. A notion that has so large a share in 
our mental Hfe must be closely examined and if possible 
explained. We must, as psychologists, take the same atti- 
tude toward it as toward the concrete experiences so far 
examined. We must seek to determine how far it is open to 
examination as a mental state, what effect it has on be- 
havior, and how the idea must have developed to the form 
that it takes at present. It is for us one phenomenon among 
many, in spite of the central position that it holds in popular 
discussion. The occasion for the development of the self 
comes from the practical needs for a distinction between 
the individual and others, and between the individual and 
the outside world. To represent these distinctions, con- 
cepts have gradually grown up in much the same way that 
concepts of external things develop, and they are hke them 
in every respect. Each has some mental content, and 
represents a large number of distinctions and processes not 

present in the idea. 

560 



THE NATURE OF THE SELF 561 

The Nature of the Self 

The Occasions for the Self-concepts. — We recognize 
not one concept of the self but many, corresponding to the 
different occasions, to the different ways, in which the outer 
must be opposed to the inner, and to the different hnes of 
division at which one may be marked off from the other. 
Three fairly general hnes of demarcation may be drawn. 
One is between the man as a whole, including the body, and 
the other individuals in society. This is the self as con- 
sidered in law and in most of the more popular objective 
discussions. A second hne of division develops, as the theo- 
retical interests become dominant, between the body and 
the mental states or consciousness. Finally, a third notion 
of the self tends to mark off the more spontaneous and 
purposive acts, those that are foreseen and consented to, 
as over against the acts induced by external forces or even 
by reflexes, — the acts that are intended, from those that 
are not intended. The first we may call the physical self, 
the second the subjective self, the third the effective self. 
It must be insisted that these hnes of division cannot be 
sharply drawn and that they are not consistent from 
moment to moment. At any particular time we are inter- 
ested only in one distinction and have no reference to the 
others. While there are many gross references and many 
occasions on which it is desirable to unite the three concepts 
into a single one, they can best be discussed separately at 
first, and then united so far as is possible in a common 
notion. In considering these concepts, one must, as in all 
cases, distinguish between the conscious element used in 
representing the self, and the meaning, — the thing or 
processes represented by that concept. 

The Physical Self. — The centre of reference of the 



562 FUNDAMENTALS OF PSYCHOLOGY 

physical self seems to be the body, partly as it is seen in 
the field of vision, partly as it is reconstructed on the basis 
of mirror images and photographs and from the references 
of friends. The meaning of this physical self is very much 
wider. It is used to refer to the body, together with many 
of the man's immediate possessions, — garments and 
adornments, and an ever-widening group of properties. 
The 'physical self gradually comes to be indistinguishable 
from the 'physically mine.' Houses and lands, friends and 
position, all of the things that one must struggle with other 
men to retain, come to form part of the physical 'me.' 
This physical self derives much of its meaning from com- 
parison with others. One tends to see one's self in relation 
to others about. The man's picture of himself and of his 
possessions always involves a comparison with others and 
with the ideals that these set for his own attainment. The 
wealth of the individual, rich and poor ahke, has increased 
enormously in the last century, but nevertheless the Une 
is quite as sharply drawn now as ever before, since the 
relative differences are approximately the same. Similarly, 
one's opinion of one's physical self in the narrowest sense 
varies with the individuals with whom one comes in contact. 
One feels one's self quite a man among small men, while 
there is a decided shrinking when with men of large stature. 
One can imagine how different Gulhver's impression of 
himself must have been when in Lilliput from what it was 
among the Brobdingnagians. This first concept represents 
the man to himself as a man among men. It is the self in 
the most practical, popular sense. 

The Subjective Self. — The second concept that repre- 
sents the self as opposed to the body is of much less general 
application, is of value in fact only in connection with more 
theoretical problems. The imaginal centre of the concept is 



THE NATURE OF THE SELF 563 

less definite; probably kinsesthetic and organic sensations 
offer what little there is of actual content. Sometimes there 
may be a picture of the self, — • as the spirit of the savage, 
or the ghost of the ignorant, — a bodily self with the physical 
characteristics subtracted, so far as that is possible. This 
seems relatively rare among psychologists, and others have 
not reported their results in sufficient numbers to afford 
much ground for generahzation. Usually one is satisfied 
with the sensations of strain in the head or in the chest as an 
embodiment of the notion of the self. Its applications, too, 
are relatively few. One pictures one's self as rising above 
bodily limitations in ill health; one opposes this self to 
the sense organs and their imperfect reports of the world. 
In psychology it is made to include consciousness as opposed 
to the activities of the nervous system which are purely 
mechanical. It is also of value in explaining dreams, in 
which the body seems to be in one place while the spirit is 
in another. When we attempt to determine to what place 
sensations are ascribed, there is Httle agreement even for 
a single sense. The skin marks the boundary of the self 
for touch; one thinks of one's self as receiving impressions 
at the surface and not at some point back in the brain. For 
hearing and sight the fine of division is not so definite. 
Most refer the sensations to the object in the outside world, 
and the hearing and seeing self is given no definite place. 
Organic sensations, particularly the strain sensations that 
come with effort, are assigned to the self as opposed to the 
body. On the sensory side, then, while every one would 
assert that mind and body are to be distinguished and that 
the 'I' is on the self side, the line of division is very vague. 
In most cases one would deny any of the seats that might 
be suggested for the processes without being able to assign 
a better. It would not even be a matter of agreement that 



564 FUNDAMENTALS OF PSYCHOLOGY 

the self in this sense included all of consciousness; nor, 
granting that, exactly how much it did include. Obviously, 
this second concept corresponds to a real need in psychologi- 
cal discussions, but equally obviously the concept is not at 
present and probably cannot be very clear cut, either in its 
image or in the limits that it makes between self and not- 
self. 

The Active Self. — The third concept of the effective 
or dynamic self represents a more real need both in psy- 
chology and in practical life. In nearly every one of the 
processes we have considered, something has been left un- 
settled in the explanation. The final presupposition upon 
which explanation of each was based had many similar 
elements in each of the processes discussed, and different 
theories sought an explanation of each of the more important 
processes in terms of some other. In attention, first, it was 
seen that there was a final factor which was characterized 
by the feeling of effort reduced in part to sensations of 
strain, the condition of which was found in social pressure. 
The resulting attention was classed as voluntary. The 
same factors were at work in the control of associations, 
and were later seen to be factors which, when present, in- 
creased the rate at which associations were formed. In 
the emotions it was found necessary to assume some tend- 
ency toward an end, some purpose that must be aided 
or hindered before emotions could appear. Finally, in 
action it is necessary and usual to distinguish simpler 
movements, that come under the head of reflex, instinct, or 
habit, from those that seem to depend upon wider knowl- 
edge and more fully conscious purpose. Each of these 
has something in common. Voluntary attention was 
explained by the social instinct ; emotion seemed dependent 
upon purposive activity of some sort; action is commonly 



THE NATURE OF THE SELF 565 

explained by attention to an idea or an end. Nor is the 
interrelation limited by these statements. Many authori- 
ties would explain movement in terms of feeling; others, 
feeling in terms of movement; still others, attention in 
terms of movement; others again, attention in terms of 
feeling, just as feeling and movement are explained by some 
in terms of attention. The common elements in all of 
these processes and the last term in the explanation of each 
are often called the self. 

The self in this sense has practically no new mental 
processes to represent it. One may think of it equally well 
as the physical self or a ghostly self. The mental content 
is indifferent to the meaning. The only sensational ele- 
ment that is at all a general concomitant is the mass of 
strain sensations so frequently mentioned as constituting 
the feeling of eiffort. These are taken to serve as an in- 
dication of activity rather than as a direct revelation of the 
self. In the attempt to analyze the factors which determine 
the course of this activity, we again have little to say. 
Our first reduction to social pressure proves, when seen in 
the light of our knowledge of instinct, to reduce largely to 
a social instinct guided by knowledge obtained from the 
society in which the man has lived. The original instinct 
we found in discussing emotions developed into a system 
of ideals, and these, as they became more active, constituted 
the purposes of the individual. The study of action offered 
no new contributions to our explanation; action was an 
outcome of ideals and purposes acting in selection. There 
was found no new impelling force, nor even any new quality 
or mental state. Study of the self adds nothing new. As 
a man studies his own self, he is aware of the fact that he is 
acting or deciding, but he gets almost no light as to what 
the process consists in. If he studies another, he can 



S66 FUNDAMENTALS OF PSYCHOLOGY 

trace certain factors that seem to play a part in making 
that individual decide as he does, but neither observation 
of one's self nor of another can show directly what the 
determining activity is. Curiously enough, tracing the 
conditions tends to discover the basis of the activities that 
are believed to be peculiarly characteristic of the self in 
society. The more intimately personal the act, the more 
objective are its conditions, the more external the forces 
that bring it about. 

In each of these more active processes, one feels that 
there is something that must be explained in terms of fac- 
tors that cannot be definitely formulated. The tendency 
is always to bring in some other simple process as the basis 
of the explanation, hence the reference from one process 
to another among mental states. But, when one sees 
that one can complete the circle and come no nearer the 
explanation in one group than in any other, it is obvious 
that going around the circle has not furthered the explana- 
tion. Two alternatives remain open. One may assume 
either that some highest process controls all the others, or 
that there are common elements in each; and then seek 
to determine what they are. The popular mind takes the 
first of the alternatives, — assumes the self as a prime 
determinant, and makes it the final force in all spontaneous 
action. Since, however, this is in reality no explanation 
but merely a tagging of the facts that are to be explained, 
it is more important to determine the elements common 
to each. This we may find in the developed ideals and 
purposes, which in turn are to be referred, first to instincts, 
then to the ideals of society taken over by the individual 
largely by virtue of the social instinct — the instinct to 
seek approval — and then tested and confirmed by his own 
individual experience. If other factors enter, they cannot 



THE NATURE OF THE SELF 567 

be traced, either in the introspection of the agent, or by a 
study of the behavior of others. In the complexity of the 
conditions that act upon the individual we are not, however, 
in a position to assert that no others are effective at any 
point. 

The Social Factors in the Self Concept. — These three 
concepts of the self tend to fuse into a single one in which 
something of each is retained, and are more or less har- 
monized into a unitary whole. The representative self 
has something of the body, something of the mental as 
opposed to the bodily, more of the strain processes that 
mark it as active. The concept is ordinarily employed 
to distinguish between the self and society, between the 
'I' and the 'You,' or, objectively, between the character- 
istics of the different individuals with whom I come in 
contact, who must be used in the accomplishment of my 
ends, or who use me in the attainment of theirs. With 
this there is a marked effect of the life in society. Both 
the static and the dynamic features of the self are ap- 
preciated only in terms of others about. One has an idea 
of one's own peculiarities only in comparison with others. 
One's notion of one's self as a whole is largely an image of 
the self as it is reflected in the consciousness of others. 
When a man is among men of smaller attainments, or 
smaller possessions, he expands; when he is with men of 
larger accomphshments or reputation or possessions, he 
shrinks just as evidently. Much of this idea of the self 
depends, not upon actual ability and possession, but upon 
the imagined attitude of others. A man becomes accus- 
tomed to act as if he were of more than ordinary importance, 
society takes him at face value, and he may go for years or 
even through Hfe without having the notion corrected either 
for himself or for others. On the other hand, a few rebuffs 



568 FUNDAMENTALS OF PSYCHOLOGY 

to a sensitive individual will repress his self in his own eyes 
and prevent any self-assertion. If he has high ability, it 
may go for years without being discovered. Society makes 
its judgment of a man in part from his own actions; and 
these in turn depend in some measure upon the estimate 
he thinks society puts upon him. The process is a cyclical 
one. The individual's estimate of himself is what he be- 
lieves to be society's estimate of him. On the other hand, 
society's estimate of the man is very largely colored by 
his estimate of himself and his consequent bearing. The 
way in which the individual pictures hunself and the esti- 
mate of his personal capacity are largely derived from the 
attitude of society toward him, just as many of the forces 
that control his active life are merely an expression of the 
society in which he lives. 

The Emotions of Self. — The activities and processes 
that develop the notion of self are found very largely in 
the emotional group. What we called the more com- 
plicated emotions, those which come from the interaction 
of the purposes of the individual with the environment, 
are largely social in character. The opposition is most 
often from other men, and the emotion is usually ascribed 
to an expanding or shrinking of the self. In fact, in much 
of our daily life, the only reason for making use of the 
notion of the self is to picture the origin and the immediate 
source of the emotion. We are concerned with the self 
only in moments of struggle and the consequent success or 
defeat. In periods of quiet contemplation of external 
objects or even in the unhindered manipulation of things, 
we are little aware of the self. With opposition, particularly 
from other men, the complex of emotions comes into play. 
We have the self-assertion of effort, the elation of victory, 
the self-depreciation of defeat. That these emotions are 



THE NATURE OF THE SELF 569 

always of a social character is seen in the fact that when 
one performs a difficult feat when alone, there is always 
a thought of what some one else might think; and the 
pleasure in the success comes largely from the background 
of realization that it is better than could have been done 
by one's rival. The onlooker is always present in thought 
if not in reality, and the resultant emotion is determined 
by the way the action would be viewed by him rather than 
by any absolute standard. 

These self-regarding emotions constitute the core of the 
idea of the self. The character of these emotions seems 
to depend upon the relation between the ambitions of the 
individual and his actual accomplishments. James puts 
it in the statement that self-esteem equals success divided 
by pretensions. When pretensions are large, success small, 
self-esteem is slight ; as success grows or ambitions diminish, 
self-esteem or self-complacency is increased. Self-esteem, 
too, is only affected when success or failure comes in some 
field in which the ambition of the individual lies. A scholar 
may very well content himself with little of the worldly 
goods, may even regard wealth as somewhat vulgar, since 
he has never set himself towards its attainment. The 
wealthy man of affairs returns the compliment by saying 
he can buy the services of a scientist much more cheaply 
than he can the advice of a financial expert, — that learn- 
ing is a drug in the market. Each is satisfied with his 
own position, with his own self, as he has never attempted 
to extend the self in the field of the other. But when men 
of affairs come into rivalry in the same field, the self of the 
one is humiliated as the other attains what he has himself 
sought. 

These emotions, or the conditions that lie behind them, 
not merely determine how the individual shall regard 



570 FUNDAMENTALS OF PSYCHOLOGY 

himself, but also play a very large part in deciding the 
degree of effectiveness of the individual. The way in which 
the self is regarded determines the attitude toward the 
problems of life, and this in turn is an important factor in 
the success or failure of the individual. The character of 
the individual, viewed either from within or from without, 
is closely related to his self-esteem. 

The man who has succeeded and lacks a sense of pro- 
portion or the saving sense of humor becomes self-conceited. 
He can no longer remove his mental gaze from contempla- 
tion of his own capacities and of past successes, nor can he 
avoid expressing this appreciation of himself, nor conceal 
his expectation that others will express their appreciation 
of that position. A child who is always the centre of the 
approving household develops an exaggerated notion of his 
own importance, and his early success in business or scholar- 
ship not infrequently sets an attitude of self-satisfaction 
that cannot be disturbed even by later failures and rebuffs. 

More striking is the expectation of failure and conse- 
quent lowering of ambitions that comes with crushing de- 
feat. A man of middle age who suddenly finds his system 
of ambitions thwarted and all of the accumulations of pre- 
vious successes swept away, seems to lose not merely all 
of his ambitions, all of his self-respect, but also the capacity 
for forming new purposes. The self disappears or is pro- 
foundly altered with the despair that follows. Numerous 
members of the drifting colonies of ne'er-do-wells of our 
large cities have been brought to their position by some 
such catastrophe. The man of means who, at first confident, 
self-assertive, and persistent, loses his wealth through some 
mischance, and fails in the first few efforts to reestablish 
himself, comes to mistrust himself and all his ventures, — 
becomes vacillating. Others lose confidence in him, and 



THE NATURE OF THE SELF 571 

he either decides that nothing is worth while, takes a care- 
free attitude toward the world and attempts nothing, or 
falls into despair and, while his ambitions are retained, 
gives up hope of realizing them. In brief, the system of ends 
feeds on success and grows as each ambition is reahzed, 
but shrinks and finally disappears with repeated failure. 
Happy is the man whose ambitions are not too different 
from his capacities and to whom environment is sufficiently 
favorable to permit the realization of ambitions in sufficient 
degree to give constant encouragement, without too great 
expansion of the notion of his capacity and importance. 

The self is in this sense an outcome of the emotions which 
arise when the S3^stem of aims receives a shock, or attains 
one of the subordinate steps toward an end or the end itself, 
although the emotions are in many cases referred to the self 
as the cause. At bottom, the two processes are probably 
one. The self is a concept that serves to explain both the 
emotions that originate from the progress toward ends and 
also the purposes themselves. Here again we seem to be 
going around in a circle. Where we seek the self, we find 
only expressions, only processes that have needed a self 
to explain them, rather than a real self. On the other hand, 
when we seek the explanation of certain of the more funda- 
mental emotions, we are said to discover evidence of the 
self, or at least a reference to the self. In other words, 
wherever we seek the self, we find something else, but when- 
ever we are seeking an explanation of spontaneous or pur- 
posive action, we find that we need, or at least wish we might 
have, a self. 

To bring together the results of our investigation, the 
self is a group of concepts originally developed to represent 
the different Hues of division between the man and others, 
between the mental and physical processes, and between 



572 FUNDAMENTALS OF PSYCHOLOGY 

the more mechanical and the more spontaneous forms of 
action. The different concepts are frequently fused, at 
least in part, into a single concept which becomes repre- 
sentative of the system of purposes as they control actions, 
which gives rise to emotions and serves to designate the 
directing forces in the more complicated mental processes. 
This concept is the point of reference for all our self -regarding 
ambitions, it is the self we are depressed about and the self 
that we exult over. Nevertheless it must not be assumed 
that something corresponding to this self need be found by 
introspection. Just as space, regarded as a concept, was 
needed to explain certain of the ways in which we saw 
objects and the possibilities of movement, so the concept 
of the self is merely a way we have of representing to our- 
selves the immediate facts found in the emotional and the 
active life, in the Ufe of decision. Examination gives us 
nothing more than does contemplation. We can analyze 
the way in which we perceive space relations into certain 
elements, we can show why we need the concept of space, 
but we do not expect to find anything more by any means. 
Similarly with the self, we can point to certain strains as 
usually present when we think ' I,' we can show why it is 
needed as a means of making certain distinctions, but we 
should not expect to find anything more by observation or 
experiment, — and we do not. 

The Continuity of the Self 

Self-identity. — Extensions of this empirically derived 
self-concept or other related concepts have been developed 
to solve certain of the more theoretical problems of psy- 
chology and metaphysics. One of the simplest of these is to 
answer the question of how the continuous, ever-changing 
series of mental processes can all be referred to the same 



THE CONTINUITY OF THE SELF 573 

self, are held together in a continuous stream, and are 
regarded as states of the perceiving self. As a matter of 
fact, the practical man is never bothered by this problem. 
In observation he is concerned only with the things that are 
meant. It is only in recognition that the fact that he has 
seen a thing before is important to him, and even then he is 
more interested in knowing that the object was in a certain 
place at a certain time than in the fact that he saw it 
there. The different experiences are held together as parts 
of a single whole by the interrelations that make recognition 
possible, that make it possible to refer each experience to 
a definite position in the series. This fact of reference is 
immediately observed. When the self-concept has devel- 
oped, the theorist makes that the point of reference, in 
spite of the difficulty in seeing how an actual substantial 
something apart from the experiences could hold them 
together. If by the self we mean the experiences themselves 
as interrelated one to the other, the notion offers less diffi- 
culty. 

The Unity of Consciousness. — Similar theories have sug- 
gested that the fact that all of the mental states form a 
unity at any moment can be explained in terms of the self- 
concept. Again it must be insisted that what is or can be 
noticed is the unity, so far as that exists, rather than an 
ego. A self in addition to the states would not give them 
unity. Rather must the unity come from the interconnec- 
tion of mental states, the subordination of all to some single 
one that is the central point of attention. As has been seen 
frequently, many processes, some corresponding only to 
partially aroused association paths, cooperate in constitut- 
ing any single experience. In part this unity is explained by 
the nervous system, in which many neurones are always 
aroused together and the action of each produces a spread 



574 FUNDAMENTALS OF PSYCHOLOGY 

of impulses to all of the others; in part it is to be referred 
to the interrelation of what might be regarded as single 
elements in the formation of concepts and meanings, the 
real mental units. In any case the unity is within the 
mental states, not a unity that comes from without through 
a connection with some single thing. In both of these 
cases, as in the more empirical active and emotional pro- 
cesses, the facts are to be found in the continuity and unity 
of mental processes ; the self-concept is developed or intro- 
duced to explain them. It is merely a method of picturing, 
not an actual experience. Here the concept is even less 
satisfactory as an explanation than it was in the preceding 
instances. 

In one respect the more cognitive processes which are 
explained by this more passive type of self may be com- 
bined with the more active discussed above. The system of 
purposes which was seen to be the deciding factor in deliber- 
ate action, and to determine the character of the emotions, 
is closely bound up with the system of knowledge. Given 
the instinctive basis, each experience modifies that instinct, 
and gives it definite content at the same time that it aids in 
the construction of our system of concepts and prepares the 
way for recognition and for meaning. In this way the two 
groups of systems become closely interwoven and are 
probably for the most part merely different expressions of 
the same fundamental unity. When active in the control 
of perception and reason, we term the result the cognitive 
processes; when acts and emotions are involved, we speak 
of purposes. All education influences each system, though 
in different degrees. The system of purposes closely deter- 
mines the acquisition of knowledge and the use made of it 
in memory and reasoning, while the knowledge obtained 
has its effects on the formation of purposes. It is the close 



DISSOCIATIONS OF THE SELF 575 

interrelation and dynamic interaction of all parts of expe- 
rience that really give a unitary character to the acts of the 
individual, determine his intellectual interests, and make 
possible the continuity of recognition and of meaning. 

Dissociations of the Self 

Dissociations of Personality. — That this interrelation 
of all parts probably has a physical basis is evident from the 
fact that in certain abnormal individuals the unity of 
memory or knowledge and of purposes may be broken up 
into two or several systems, each of which acts alone to 
produce all the capacities of a whole individual, but which 
differ in the characteristics of each of the partial personali- 
ties. The cases of alternating or dissociated personality 
offer much of dramatic interest, which cannot be treated 
here. A person who may be in fair health will suddenly find 
himself in a strange situation, with no memory of anything 
that has happened before. In one case even the most rudi- 
mentary knowledge of simple things was lost, and some days 
were required for the patient to recognize simple objects, 
and still longer to learn to speak. For a long time this 
second set of experiences remained cut off from the old, then 
finally the patient awoke again with no memory for recent 
events, as if he had just waked up into the first set of expe- 
riences. In most cases the second self comes into being 
with a portion of the original memories and experiences of 
the old. There is a dissociation of the old into two or more 
parts, rather than a development of an entirely new series. 
The patient suddenly wakes in an unfamiliar environment, 
with no memories of where he may be or of recent events, 
but with full command of language and the ability to inter- 
pret the objects about. After that the different personalities 
or groups of experiences will alternate. The time occupied 



576 FUNDAMENTALS OF PSYCHOLOGY 

by one self varies greatly, as does the occasion for the change 
from one to another. 

Characteristics of the Partial Selves. — If we relate the 
characteristics in which the selves vary, and the marks 
that distinguish them one from the other, to the facts that 
have led to the development of the self-concept, we find 
that practically all of them may be closely paralleled. One 
element in the consciousness of self is the persistence of 
various organic sensations. One feels at home in the body, 
if we may indulge in metaphor, because the strain sensations 
are constant from one time to another. Ribot reports some 
cases of spht personality in which the organic sensations 
were changed, and suggests that the change might in part 
have accounted for the alteration. Much more important 
is the break in the line of association, the inability to recall 
an event in one state which has occurred in another. The 
train of memories seems to be broken off sharply when the 
personality alternates. Everything that happened in one 
state can be recalled in that state, but all the experiences 
of the other state are lost. There is, furthermore, no recog- 
nition in one state of the objects seen in another. The asso- 
ciations that connected them originally are completely 
broken, while the associations within each group persist. 
It is this characteristic that gives the name of dissociated 
personality. In the dissociation there seem to be peculiar 
divisions of the original self. In the Beauchamp case, 
reported by Dr. Prince, one self kept the knowledge of 
French of the original, while the others were entirely with- 
out it; and other acquirements seemed to be assigned to 
one alone of the personalities. 

Not merely are the acquirements differently divided, but 
the active and emotional characteristics seem also to vary. 
One self will be highly conventional in action and desires. 



DISSOCIATIONS OF THE SELF 577 

will respond very quickly to social instincts, the other will 
be entirely arbitrary in action. The difference may ap- 
proach that so vividly pictured by Stevenson in his story 
of Dr. Jekyll and Mr. Hyde. The purposes of the two selves 
are different, as are also the memories. This is in accordance 
with our explanation of the development of ideals by the 
action of the accumulated experiences. When the systems 
of knowledge divide, the control exerted by each of the 
two sets of ideals or purposes is exerted differently according 
to the components that make it up. Dr. Prince suggests 
that in certain cases the instincts as well seem to be divided. 
One self will take most of the tender and benevolent in- 
stincts, the other most of the aggressive, the rebellious, 
anti-social instincts. Where one self will be painfully con- 
scientious and considerate of others, the second will be 
altogether selfish and indifferent to the ordinary family and 
social welfare. With the break in knowledge, there goes a 
corresponding sudden alternation in the effective self. The 
individual shows different emotions, is differently controlled 
in action and in thought. Aside from the fact that both 
selves are still in the same body, they are essentially two 
individuals, two selves. There is no memory or recognition 
of events that occur to the other self, there is no consistency 
of action between them, there is no continuous self-con- 
sciousness from one to the other. Both the theoretical and 
practical characteristics of the two selves are altered. 

The Phenomenon of Dissociation. — If we attempt an 
explanation from the physical side, it would seem that the 
various effects upon the nervous system are retained and 
organized into systems ; that these systems, while ordinarily 
acting as units, may by certain shocks be dissociated along 
somewhat definite Hnes of cleavage that also develop as a 
result of the formation of distinct systems. When the 



578 FUNDAMENTALS OF PSYCHOLOGY 

break comes, we have each system or group of systems 
persisting, but with no bonds of connections between them. 
Each system continues to act alone, and to control the 
responses through the persistent nervous connections, 
guided by the wider series of partially active neurones. 
In most cases certain of the more frequent nervous activities 
are common to the two systems, but this shows itself only 
in the persistence of the nervous correlates of more general 
concepts and ideas, to which each of the new experiences 
may be referred and be understood, with none of the more 
specific references that constitute recognition. The normal 
self has as its correlate on the physical side a complete 
system or system of systems, from all of the more important 
parts of which impulses may pass to awaken all of the other 
parts, — a system that embraces and unifies many lesser 
systems, all of which are connected. So long as this system 
remains unbroken, memory is continuous, memories from 
all parts of the life may be recognized, and the actions are 
sufficiently controlled to be consistent. That this is the 
basis for the characteristics that we have regarded as con- 
stituting the peculiar condition of the self is evident from 
the fact that, when this complete system is broken into 
two or more groups of systems, two or more selves make 
their appearance. 

Hjrpnotism and Other Forms of Dissociation. — Not 
only does dissociation arise spontaneously, but in many 
individuals it may be induced at will. If, for example, 
a patient be asked to keep attention continuously fixed 
upon some one object, he will pass into a cataleptic stage, 
his muscles will stiffen, and he will gradually to all appear- 
ances become unconscious, and in the higher degrees of the 
resulting abnormal condition will show many of the phases 
of the dissociated personahty. The state is much more 



THE SELF AS THE WHOLE MAN ACTIVE 579 

readily induced if the patient remains passive and is told 
from time to time that he is going to sleep. When most 
completely hypnotized, the patient is highly suggestible, 
will do anything that he is told to do, may even be made 
to take on different personalities. On waking there is 
ordinarily no memory of what has happened during the 
hypnotic state, although when hypnotized again, the person 
may recall the events of this period. The close relation 
between this and the phenomena of the dissociated self is 
indicated by the fact that change from one self to the other 
often can be induced by suggestion in the hypnotized state 
and that when hypnotized in one state, that self will recall 
events experienced in other states. In many diseased 
conditions there is evidence that partial dissociation of 
these systems may take place and may be responsible for 
the disease. Hysteria is largely, if not altogether, due to 
a breaking away from the whole of some one of the systems. 
This may not be large enough seriously to disturb the higher 
coordinations of the self, but does prevent the larger system 
from receiving impressions from certain sense organs con- 
nected with the dissociated elements, and may also cause 
a paralysis of the muscles that are either permanently or 
temporarily united with those dissociated elements. 

The Self as the Whole Man Active 

Consciousness and Subconsciousness. — Numerous 
theories have suggested that the self is seldom completely 
united, that there are always larger or smaller groups of 
experiences or memories which are independent of the 
larger system. Thus, Freud, as we have seen, explains 
dreams and many of the accidents of daily Ufe as well as 
the witty sayings of the normal individual by the fact that 
he has an organized complex of elements, which usually 



58o FUNDAMENTALS OF PSYCHOLOGY 

contributes little to consciousness but which on occasion 
will be excited and when aroused open new possibilities 
for good or evil in the individual. This detached complex 
is frequently said to have all of the elements of the normal 
or total self, to have desires of its own, to do thinking for 
itself, — in fact, to constitute a true self, which is also 
regarded as having a kind of consciousness. Many facts 
point to the presence of these complexes, and the assertion 
that a definite consciousness attaches to them raises many 
questions as to what our ordinary consciousness may be, 
upon what it depends. It must be granted that these 
subconscious systems give rise to many, if not all, of the 
effects of the complete system. We could personify them 
as readily as we do the experience of many other individuals. 
The only test of consciousness from the inside, however, 
is the personal test — that we are aware of it in intro- 
spection — and by definition this subconscious does not 
belong to that class. 

However, so many of the determinants of our personal 
consciousness are not themselves directly conscious that 
the difference may not be important. Of all of the myriad 
activities in the nervous system, only a few can be known 
at any moment; and, as has become apparent from the 
study of meaning and related processes, no one of these is 
consciousness, of and for itself alone. It must always 
be grouped with a number of other activities, if conscious- 
ness is to result. Even then consciousness is limited, in 
most cases, to the things referred to or meant, rather than 
to the elements that are supposed to carry the meaning. 
Each group of nervous elements may by its activity con- 
tribute to the consciousness of the total, but the conditions 
of consciousness must still be regarded as obscure. The 
most that can be said is that of the different systems which 



THE SELF AS THE WHOLE MAN ACTIVE 581 

are found within the nervous system at any one time, the 
largest and most active is accompanied by consciousness. 
The others are either completely suppressed, as in the case 
of the complexes of the subconscious or unconscious, or 
the minor systems contribute only in some slight degree 
to the total consciousness. Consciousness seems to be 
determined by or to accompany the activity of a system 
of nervous elements, connected by virtue of acting together 
in various systems of experiences. How many elements 
may be included in what corresponds to the centre of con- 
sciousness, and how far less central elements can play a 
part, no one can say. It can be asserted with assurance 
that even the most central features of consciousness cor- 
respond to the action of many neurones, show the effect of 
many experiences, and represent even more. Where the 
limits are to be drawn is not to be confidently stated. 

The Self and the Individual. — Very little of the nervous 
action is really accompanied by consciousness, although 
a very large part of that activity has an effect upon con- 
sciousness. Much the same statement may be made of the 
functions of the individual, as we deal with him in psychol- 
ogy and everyday life. We know that he remembers and 
recognizes, that he perceives objects, and reaches con- 
clusions, that he feels and chooses; we can even trace many 
of the conditions of these different operations, but he him- 
self is conscious of little more than the outcome, — the 
causes are not revealed in consciousness. There is no oc- 
casion, then, to spend much time on the question whether 
some of the hidden complexes of neural activities are accom- 
panied by consciousness, when we know so little of the 
causes and effects of the highest, most fully revealed 
consciousness. 

A close analysis of self-consciousness gives as little re- 



582 FUNDAMENTALS OF PSYCHOLOGY 

ward. One has certain concepts which are represented 
by more or less definite imagery, but again the important 
factor is not the imagery but what the imagery represents. 
This is our notion of the whole as active, of the processes 
that direct our thoughts and acts, a continuous experience, 
with the possibility of referring from any part to any other. 
All these are involved in the self idea, but are not all con- 
scious at any time. The consciousness of self is seldom 
present and is of Httle importance when present, the self 
as the whole man active, as the unity and continuity of 
experience, is fundamental. It must be emphasized that 
this is not a single experience among the other experiences, 
it is not something of which we may become immediately 
conscious; on the contrary it is the man with all of his 
experiences and activities viewed as a whole. 

REFERENCES 

James: Principles of Psychology, Vol. I, Chs. IX, X. 
Cooley: Human Nature and the Social Order. 
Ribot: The Diseases of Personality. 
Prince: The Dissociation of a Personality. 



INDEX OF NAMES 



Ach, 529, 531, 537. ■ 
Alrutz, 160/. 
Angell, Frank, 300. 
Angell, J. R., 14, 327. 
Arai, 541. 
Aristotle, 246. 
Aronsohn, 178. 
AschafFenburg, 284. 
Atwood, 546. 

Bagley, W. C, 361. 
Bair, 386, 513, 515, 537. 
Barany, 58. 
Barrett, 532/. 
Batson, 518. 
Berussi, 356. 
Berman, 507. 
Bezold, 154. 
Biedermann, 196. 
Bills, Marian, 126. 
Bing, 92. 
Bllx, 158. 
Book, 515. 
Boring, 170. 
Bourdon, 311, 343. 
Breed, 234. 
Breuer, 183. 
Broca, 64-70. 
BrowTi, Crum, 183. 
Bromi, Thomas, 181. 
Brum, 143. 
Bryan, 515, 517. 
Burdach, 42 /. 

Caesar, 274. 

Calkins, Alary W., 286. 
Cannon, 188, 487, 490/. 
Carlson, 188. 
Charcot, 259. 
Chevreul, 170. 
Claparede, 557. 
Clifford, 90. 
Coleridge, 383. 
Colvin, 406. 



Coole}-, 582. 
Courtier, 472. 
Craig, W. C, 225. 
Cashing, 66. 

Dal ton, 116. 

Darwin, 437/, 494 f, 507- 
Davies, 170. 
Dawes-Hicks, ^^3- 
Descartes, 480/. 
Dewe}^, 440, 497. 
Diamandi, 403. 
Dodge, 262, 364, 542. 
Dallenbach, 367. 
Donaldson, 158. 
Dunlap, 92. 

Ebbinghaus, 198, 286, 368, 369, 370, 

371, 376, 378, 380/, 386/, 3Q8. 
Edelmann, 143. 
Ellis, Havelock, 452. 
Erdmann, 364. 

Fabre, 220. 

Fechner, 11, 194, 195, 197, 245. 
Ferree, 347, 349. 
Flechsig, 68. 
Flourens, 64. 
Franz, 69, 514 
Freud, 446/, 457, 502, 579. 
von Frey, 160, 162, 164, 167, 182, 
197, 302. 

Galen, 505, 507. 

Gall, 63. 

Galton, 211, 259, 264, 286. 

Goddard, 210. 

Goldscheider, 158, 162, 164, 181 ff , 

302. 
Goll, 63. 
Gowers, 44. 
Gray, 364. 
Greenwood, 135. 
Griffitts, 261, 542, 550. 



583 



584 



INDEX OF NAMES 



Hardesty, 156. 

Harter, 515, 517. 

Haycraft, 179. 

Hayden, 390. 

Haj^ward, 390. 

Head, 164, 168, 170. 

Heller, 328. 

Heknholtz, 112/, 116, 123, 128, 129, 

131- 134/, 151, iS3» 157, 191- 343- 
Henning, 178/, 181. 
Hensen, 155. 
Hering, 82, 112, 116, 123, 132 ff, 

159, 244, 307- 
Hermann, 145. 
Herrick, 59, 92. 
Hobbes, 93. 
Hobhaus, 220. 
Hodge, 545. 
HoUingworth, 390. 
Howell, 59, 135, 157. 
Huey, 364. 
Hunter, 347, 349. 

Inaudi, 403. 

James, 240, 343, 356, 413, 435, 484, 

486/, 491, 507, 525, 569, 582. 
Jastrow, 420, 507. 
Jennings, 18, 512. 
Jost, 375, 377/. 
Judd, 333. 

Kent, 248. 

Kiesow, 175. 

Koehler, 145. 

Koenig, 145. 

Kraepelin, 539, 541. 

Kreidl, 186. 

von Kries, 116, 123, 133.^. 

Kulpe, 255 /, 414, 464. 

Ladd, 92, 157, 181, 343, 356, 537. 

Ladd-Franklin, Mrs., 135. 

Lange, 484. 

Langefeld, 524. 

Langley, 197. 

Lasher, 514. 

Lee, 559. 

Leonardo da Vinci, 113. 

Lewis, 542, 544, 546, 550. 

Liepmann, 75. 

Lipps, 477. 

Locke, 93, 339. 



Long, Constance, 457. 
Lotze, 300/. 
Lowitt, 196. 
Luft, 143. 

MacDougall, W., 92, 224, 240, 251, 

264, 480, 493, 504. 
Mach, 183. 
Malthus, 438. 
Marshall, H. R., 479. 
Martin, Lillien J., 256. 
Mayer, 149. 
Meumann, 371, 374, 375, 379, 398, 

402 f, 406. 
Meyer, Adolf, 71. 
Meyer, Max, 156. 
Mever, S. C, 395. 
Michotte, 531/. 
Mill, 181. 
Miiller, G. E., 133, 198, 245, 369, 

373, 379, 382, 385, 399, 406, 559. 
Miiller, H., 107. 
Miiller, Johannes, 311. 
Monakow, von, 92. 
Morgan, J. B., 276, 293. 
Morgan, Lloyd, 217, 240. 
Mosso, 544. 
Mulhall, Miss, 390. 
Muscio, 559. 
Myers, 135, 157, 263, 327, 356. 

Nagel, 192. 

Oehrwall, 173. 
Ogden, 378. 

Parsons, 135. 

Pawlow, 472, 487. 

Pearson, 211. 

Perkins, Nellie, 376. 

Pieron, 557, 559. 

Pillsbury, 182, 240, 293, 364, 440. 

Pilzecker, 245. 

Piper, 36. 

Plato, 421, 484. 

Prince, Morton, 577/, 582. 

Priim, 532. 

Pulfrich, 311. 

Pyle, 374. 

Radossawljewitsch, 387, 397. 
Rayleigh, Lord, 326. 
Ribot, 507, 582. 



INDEX OF NAMES 



585 



Rivers, 168, 170, 457 557. 
Rosanoff, 248. 
Royce, 467/- 
Ruckle, 399, 402. 
Russell, Bertrand, 14. 
Rutherford, 155. 

Sanford, 379. 

Schaeffer, 92. 

Schaeffer, H., 157. 

Schumann, 369, 379, 382, 385. 

Scriabin, 263. 

Shand, 480/, 507. 

Shepard, 385, 450, 472, 556, 559. 

Sherrington, 79, 82/, 487, 490/, 

498/ 
Skaggs, 379. 
SoUier, 485. 
Spinoza, 481. 
Spurzheim, 63. 
Steffens, Miss, 373 /. 
Stern, 345. 
Stewart, 326. 
Stout, 477, 504. 
Stratton, 304. 
Streeter, 58, 186. 
Strieker, 260,' 264. 
Strong, C. A., 92. 
Strong, E. K., 390. 
Swift, 515, 537. 

Terman, 203/. 

Thorndike, 511. 

Thunberg, 161. 

Titchener, 135, 181, 267/, 293, 356, 

440. 
Trotter, 170. 



Ulrich, 376. 
Urbantschisch, 149. 

Villiger, 59. 
Vogelsonger, 385. 
Voikmann, 302. 

Wallace, 437 Jf. 

Waller, 19S. 

Warren, 14, 479. 

Watson, 6, 14, 224, 240, 250, 507, 

513- 
Watt, 157. 
Weber, 195. 
Wernicke, 70. 
Wheatstone, 320. 
Wien, 196/. 
Wirth, 268. 
Witasek, 343, 379. 
Wohlgemuth, 349. 
Wolfe, 389 /, 398. 
Wolff, II. 
Wood, 211. 
Woodrow, 350, 352. 
Woodworth, 14, 92, 157, 181, 264, 

268, 343, 356, 414, 457, 475, 477, 

521, 537- 
Wundt, II, 197, 266, 268, 304, 332, 

468/, 472, 505. 

Yerkes, 218. 
Yoakum, 218. 
Young, 112, 116, 131. 
Yule, 209. 

Zander, 176. 
Zeitler, 357. 
Zwaardemaaker, 181. 



SUBJECT INDEX 



Abnormal psycholog}^ 13. 
Accommodation in the perception of 
depth, 314; mechanism of, loi/. 
Achromatic series, 119^. 
Acquisition of skill, 515-520. 
Action, 508-537. 
Adaptation, visual, 120/, 126. 
Adrenal glands, 87; in emotion, 



Affection and feeling, 458 _/; bodily 
changes in, 471 ff; not sensation, 
460-464; qualities of , 466 _^. 

After-images in movement, 346; 
negative, 117; ringing off of, 128. 

Anatomy and psychology, 8 /. 

Angle illusions, 335/. 

Animal psj'chology, 12. 

Aphasia, 70^. 

Apraxia, 74/. 

Areas, minimum visual, 130. 

Association, 246-252; control of, 
284-289; laws of , 246 _/; nervous 
basis of, 249 /. 

Attention, 265-294; and intensity. 
266 /; conditions of, 277-284 
effort and, 289; forms of, 288-291 
nature of, 265 /; physiological 
basis of, 291; range of, 273/. 

Attributes of sensation, 95 /. 

Audition, limits of, 142 /. 

Auditory nerve, connections of, 53. 

Auditory space, 325-329; in the 
blind, 328. 

Autonomic nervous system, 84 /. 

Axone, 22/. 

Basilar membrane 142, 151/. 

Beats, 146. 

Behaviorism, 6 /. 

Behavior of lower organisms, 15 ^. 

Belief, 430.^. 

Binocular vision, 309 ff. 

Body and mind, relation of, 88 ff. 



Born blind, space perception of, 

337/- 
Brain, development of, 33 ^. 
Brain stem, functions of, 46/; paths 

in, 48 _^; structures of, 47/. 

Cerebellum, 57/. 

Cerebral localization, 62 ff. 

Cerebrum, parts of, 60/. 

Character, 201. 

Character tests, 207 /. 

Child study, 12. 

Chinese symbols as concepts, 418. 

Choice, 528-531. 

Circulation, changes of, in affection, 

472/. 
Clearness and attention, 267/. 
Cochlea, structure of, 140/. 
Coefficient of correlation, 208 /. 
Cognition and recognition, 396 /. 
Cold spots, 158/. 
Color blindness, iisff. 
Color mixture, in/. 
Color pyramid, log ff. 
Complementary colors, 14 /. 
Concept, 414-424; and perception, 

362 ff; self as, 561 f; space as, 

341/- 
Concepts, development of, 417 /; 

use of in reasoning, 422/. 
Conditioned reflex, 250. 
Cones, 104 /; contraction of, 108. 
Confluxion and contrast as theory of 

illusion, 334. 
Consciousness, 4 ff; and movement, 

520/; unity of, 573. 
Consonants, Helmholtz theory of, 

148. 
Contrast, 118. 
Control of emotions, 501. 
Convergence in perception of depth, 

315/- 
Cord, reflexes in, 39 ff. 



586 



SUBJECT INDEX 



587 



Corpora quadrigemina, function of, 

59- 
Corresponding points, 310. 
Cortex, association areas in, 68 f; 

motor areas in, 65/; sensory areas 

in, 66 /. 
Cutaneous sensations, 157-170; sense 

organs, i66jf. 

Deduction, 433. 

Definitions of psychology, 3 ff. 

Dendrite, 22/. 

Depth, perception of, 314-324. 

Deuternope, 124. Jf. 

Distraction and attention, 276. 

Distributed repetitions in learning, 

375/-. 

Double images, 316 Jf. 

Drainage, law of, 250/. 

Dreams, 448-451. 

Ductless glands, 85 ff; in tempera- 
ment, 506/. 

Duplicity theory, 120 f. 

Duration of sensation, 96 /. 

Ear, structure of, 98.^. 

Economics and psychology, 10. 

Education and attention, 281. 

Effort as muscular strain, 271. 

Emotion, 480-508. 

Emotions, classification of, 498 /; 
in self, 568/. 

Empathy, 477. 

Empiricism, 338-341. 

Epicritic sensibility, 169. 

Evolution, discovery of as illustra- 
tion of reasoning, 437.^. 

Extent of sensation, 96 /. 

Eye, dioptrics of, 102 Jf; structure 
of, 98/. 

Eye-movements, 307/. 

Eye-muscles, 306 f. 

Facilitation and attention, 291 /; 

of nervous impulses, 81/. 
Fatigue, 538-556; bodily changes 

in, 548 /; mental, 546 /. 
Fears, instinctive, 226/. 
Feeling, 458-480; theories of, 474- 

.478- 
Fifth nerve, connections of, 53 /. 
Fissure of Sylvius, development of, 
34/. 



Flechsig, tracts of, 43 /. 
Fluctuations of attention, 274^. 
Forgetting, curve of, 380 /; Freud's 

theory of, 452. 
Fovea, 106 jff. 

Freedom of the will, 534-537. 
Fusion, tonal, 147/. 

Genetic psychology, 12. 
Goal idea, 284/. 
Goll, columns of, 42 /. 
Gregariousness, 229/. 

Habit, and the synapse, 80; forma- 
tion of, 212 ff. 

Hearing, theories of, 151. 

Helmholtz theory of color, 131. 

Hemispheres, development of, 35 /. 

Heredity, and attention, 283 /; 
mental, 199/. 

Hering theory of vision, 132/. 

Horopter, 3 1 2 _^. 

Hunger, 188. 

Hypnotism, 578/. 

Imageless thought, 413/. 

Imagery t3q3es, 258-263; and mem- 
ory, 402 /; concrete types of, 
201 /; verbal, 260 /. 

Images, mental, 254-258; projec- 
tion of, 256/. 

Imagination, 441-457. 

Imitation, 235/; in learning, 519/. 

Incentives in movement, 522/. 

Individual differences in memory, 
401. 

Induction, 435 /. 

Industry, fatigue in, 548/. 

Inference, 427-430. 

Inheritance, mental, 210 Jf. 

Inhibition and attention, 291 /; 
associative, 379; of nervous im- 
pulses, 82 /; reproductive, 385 /; 
retroactive, 382. 

Instinct, 219-241; classification of, 
224 /; definitions of, 219 Jf; in 
learning, 234 /; in the control of 
habit, 216; origin of, 237-240; of 
infancy, 225/; social, 229-233. 

Intelligence, 201 Jf; distribution of, 
204 Jf; tests, 202 J'; quotient, 
203 /. 

Intensity of sensation, 96. 



588 



SUBJECT INDEX 



Interactionism, 89. 
Interest and attention, 290. 
Introspection, 2 /. 
Irradiation, 129. 

James-Lange theory of emotion, 

484/- 
Jost's Law, 377, 382. 
Judgment, 424-427. 

Kinaesthetic sensations, iSi Jf. 

Ladd-Franklin Color Theory, 133. 

Language, development of, 235 /. 

Learning in animals, 511 /; Laws 
of rote, 369-380; by wholes pref- 
erable, 373 /. 

Limen of twoness, 301 Jf. 

Localization, spatial, theories of, 
305 /; cerebral, 63-69. 

Meaning, 410-414; and movement, 

522; and recognition, 395. 
Memory, 365-407; after-image, 

244/; image, 244; systems, 404 /; 

Training of, 405; Methods of 

investigating, 368/. 
Mental age, 203. 
Methods of psychology, 2 /. 
Mimetic movements, 270. 
Mind, 3/. 
Mood, 504. 
Motion and aid to depth perception, 

323 f- 
Motor phenomena in attention, 268- 

272. 
Movement and perception, 296 /; 

and sensation, 509 
Miiller-Lyer illusion, 331 Jf. 
Myths, symbolism in, 453. 

Nativism, as theory of space, 338- 

341- 

Nerve impulse, theory of, 37.^. 

Nervous system, 15-93; develop- 
ment of, 27_^; parts of, 24^. 

Neurones, structure and functions 
of, 20/. 

Noise, nature of, 150/. 

Observation, 2 /. 
Observational memory, 366 Jf. 
Olfactory sensations, 176-181. 



Optic nerve, connections of, 53. 
Optical illusions, 329-337. 
Organic sensations, 188 ff. 
Origin of emotions, 494 _ff. 

Pain, sensations of, 162 f. 

Perception, 294-364; and associa- 
tion, 294 /; as concept, 295 /; of 
space, 298-344. 

Peripheral vision, 116. 

Perseveration, 245 /; and distributed 
repetitions, 377; and forgetting, 
382; in retroactive inhibition, 382. 

Perspective in depth perception, 322. 

Phase difference in perception of 
direction of sounds, 326. 

Philosophy and psychology, 10. 

Physiological psychology, 11. 

Pituitary body, 86 /. 

Play as instinct, 236 /; imagination 
and, 442 _^. 

Pleasure as guide to learning 217. 

Practice, 540. 

Pressure, sensations of, 160 Jf. 

Primary colors, 112/. 

Proof, 433, 437. 

Protanope, 125/. 

Protopathic sensibility, 169. 

Pseudoscope, 319. 

Psychophysical parallelism, 89 ff. 

Pupillary reflexes, 56/, 100/. 

Purkinje phenomenon, 122/. 

Purpose as condition of attention, 
279; as sine qua non of emotion, 
482. 

Pyramidal tract, 44 /. 

Quality of sensation, 96. 

Reading, 357-360. 

Reasoning, 407-440; active stages 
in, 409. 

Recall, 384-387. 

Recognition, 387-397; association 
theory of, 391 f; motor theory of, 
394; feeling theory of, 395. 

Refle.x, determination of, 38 /. 

Reflexes in the brain stem, 56/. 

Remote sensations in movement, 

525/- 
Resident sensations in movement, 

526/. 



SUBJECT INDEX 



589 



Restitution of cerebral functions, 
76. 

Retention, 242-246; nature of, 
242/,' and habit, 243 /; and for- 
getting, 380-384. 

Retina, structure of, 104 _^. 

Retinal image, formation of, 102 /. 

Revery, 444-446. 

Rhythm, 340/; in learning, 372/. 

Righthandedness, 74/. 

Rods, 104/. 

Rote memory, 368-387. 

Seasickness, 187. 

Selection, attention as, 268. 

Self, 560^582. 

Sensation, 93-198. 

Sensations, classification of, 94 /; 

intensity of, 193 /; intensity and 

affection, 470; centrally aroused, 

254-258. 
Sentiment, 503 /. 

Shadows in depth perception, 324/. 
Sight, sensations of, 97-135. 
Sleep, 556-560. 
Smell, sensations of, 178/. 
Social forces in attention, 282/. 
Social pressure, 232/. 
Social psychology, 12; factors in the 

self, 567/. 
Sociology and psychology, 10. 
Space perception, theories of, 337- 

343- 
Spatial phenomena of vision, 129. 
Specific energies, doctrines of, 94 Jf, 

190/. 
Spectral colors, iiiJF- 
Spectrum, range of, 97/. 
Speech, perception of, 360. 
Static sense, 183-185. 
Stereoscope, 318/. 
Suggestion, 246. 
Syllogism, 434/. 
Symbolism in dreams, 448 /. 
Sympathetic system in emotions, 

487/. 
Sympathy, 230/. 



Synaesthesia, 263/. 
Synapse, 40, 77/. 

'T'-shaped cells, 32/. 

Tactual space, 2ggjf. 

Taste, sensations of, 170-176; sense 
organs of, 172/; nerves of, 176; 
and chemical composition, 173. 

Teleostereoscope, 320/. 

Telephone theories of hearing, issjf- 

Temperament; 201, 505. 

Temperature, sensations of, 158 _ff; 
scale, 160 Jf. 

Temporal phenomena in vision, 
126/. 

Tests, Binet, 202 jj; Army, 205/. 

Thalamus, functions of, 59. 

Thirst, 189. 

Thyroid gland, 86. 

Timbre as aid to perception of direc- 
tion of sounds, 327. 

Time, perception of, 352, 356. 

Tonal qualities, 1^2 jf. 

Tone, sensations of, 136-157; color, 

144/- 

Tones, difference, 149/. 

Tracts in cord, 42 jf. 

Trial and error in learning a move- 
ment, 510-520; mental processes, 

213/- 

Unconscious, the, Freud's theory of, 
446-451. 

Vesicles, brain, 34. 

Vestibule, structure of, 183/. 

Vision, stimulus for, 97. 

Visual movement, perception of, 

.344-349- 
Visual purple, 108. 
Vowels, qualities of, 145 /. 

Warm spots, 158 ff. 
Weber's Law, 193-199. 
Wit, Freud's theory of, 453 /. 
Witness, memory of, 366 Jf. 
Work, 538. 



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